Search

Cigarette smoke is associated to severe chronic diseases. The most harmful components of cigarette smoke derive from the combustion process, which are significantly reduced in the electronic cigarette aerosol, thus providing a valid option in harm reduction strategies. To develop safer products, it is therefore necessary to screen electronic cigarette liquids (e-liquids) to meet high safety standards defined by government regulations. The aim of the present study was to evaluate the presence of metal- and plastic-derived contaminants in four different commercial e-liquids with high concentration of nicotine and their cytotoxic effect in normal human bronchial epithelial cells by a number of in vitro assays, in comparison with the 1R6F reference cigarette, using an air-liquid interface (ALI) exposure system. Moreover, we evaluated the effect of aerosol exposure on oxidative stress by measuring the production of reactive oxygen species and mitochondrial potential. Our results showed no contaminants in all e-liquids and a significantly reduced cytotoxic effect of e-liquid aerosol compared to cigarette smoke as well as a maintained mitochondria integrity. Moreover, no production of reactive oxygen species was detected with e-cigarette aerosol. In conclusion, these results support the reduced toxicity potential of e-cigs compared to tobacco cigarettes in an in vitro model resembling real life smoke exposure.

In seismic prone areas ecclesiastical masonry complexes have shown a very highvulnerability, as detected after the last Italian earthquakes, such as those occurred in L'Aquila(2009), Emilia-Romagna (2012), Central Italy (2016), and Ischia (2017). These are particulartypes of aggregate buildings subjected often to partial collapses, due to the presence of highlyvulnerable elements, like the bell towers. Preliminary analyses should including straightforwardand quick methods are necessary. In this paper the bell tower vulnerability is analyzed takinginto account the rocking behaviour of the tower only and considering the contribute of the entireecclesiastical complex as a rigid body sliding with a fixed friction coefficient with respect tothe foundations. It is shown that suitable values of maximum oscillations and horizontaldisplacements are obtained. The case study is the ecclesiastical complex of S. Anna in Cervino(Caserta, Italy).

Unreinforced masonry is the most diffused construction material in the major part of historical centers in Europe. In a building subjected to earthquake forces the contribution of in-plane shear resistance of the masonry walls is a determinant factor for the stability of the whole structure. In particular, the masonry piers are the structural elements subjected to the combination of normal and shear forces. In general, ductile tools to model the in plane behaviour of masonry are always welcome in order to evaluate the capacity of walls subjected to vertical and horizontal actions. In this framework, two no-tension approaches to model the behaviour of masonry walls loaded with in-plane forces, involving a minimum energy procedure, are presented. Both the procedures allow the representation of the stress maps in the panel in case of monotonic increase of shear load. The results of the numerical analyses are compared and discussed., Frattura ed Integrità Strutturale, 14 (51)

The methodical study of safeguard of artistic heritage and other devices subjected to earthquake and, in general, to time-dependent forces has considerably spreaded in the last years, thus increasing researchers’ interest in problems concerning motions of rigid objects simply supported on a base plane. The behaviour of piece of equipments, statues, storage tanks, or even tall buildings has been in fact studied as that of rigid bodies with relation to different base excitations. In some cases, the possibility of influencing the quality of motion can be a strong tool to reduce vulnerability, like in the cases in which rocking motion is to be avoided and sliding motion is welcome. This paper focuses the attention on this last problem. This is the same large class of both non-structural and structural elements that can lose their functionality because of earthquake motions. The results of numerical modelling of sliding and rocking motion in presence of both different excitations and mechanical parameters are presented and compared with experimental data performed by the authors. The results developed are in good agreement with the laboratory tests, and this assures the reliability of both the analytical procedure and the determination of the parameters involved.

The interest of the scientific community for the seismic behaviour of existing masonry buildings has largely increased in recent years, due to the fact that the seismic events have evidenced a great need of rehabilitation. Masonry structures, and especially low rise buildings, are in fact the most diffused all over the world and in particular in seismic areas in developing countries because of their ease in construction and economy. Moreover unreinforced masonry is the most diffused construction material in the major part of historical centrers in Europe. In a well engineered and constructed masonry building subjected to earthquake forces, in which out of plane mechanisms can be avoided, the contribution of in-plane shear resistance of the masonry walls is a determinant factor for the stability of the whole structure. Based on this last consideration, this paper presents an approach for the analysis of masonry walls loaded with in-plane forces, involving a minimum energy procedure. The results of the numerical analyses presented are compared with those obtained by laboratory tests on brick masonry panels.

The seismic protection of objects contained within museums is a topic of great interest, especially with reference to how they are displayed or stored. This problem is the same as that of a large class of non-structural components, such as mechanical and electrical hospital and laboratory equipment that could lose their functionality because of earthquakes. Statues and ceramics simply supported on the floor represent a significant set of case. In some cases, like the Bronzes of Riace, isolation systems have been developed. However, in general museum exhibits are not equipped with devices capable of mitigating the oscillations induced by possible earthquakes. The case study of a marble statue placed on a freestanding squat rigid pedestal is examined. The system of algebraic differential equations governing the problem has been derived and included in an ad-hoc numerical procedure. It is shown that the insertion of a squat rigid body with low frictional resistance at the lower interface with the floor, and high frictional resistance at the upper interface with the artifact significantly reduces the amplitude of the rocking response. As a result the artifact rocks without sliding on the rigid base that slides without rocking with respect to the floor. The numerical analysis performed can be a tool to help in the choice of the optimal friction values in the surfaces of the flat block, designed as a simple isolation system.

The safeguard of museum exhibits like vases and statues, laboratory equipments, storage tanks, or even tall buildings and other structural elements subjected to earthquake and in general to time-dependent forces has been in the last years a topic focus. The classical mechanical problem of the motions of rigid objects simply supported on a base plane, developed in the first year of sixties, thanks to the seminal paper by Housner on the inverted pendulum, can be now take advance due to the development of calculation tools. In some cases the quality of motion can be determined varying the material parameters involved. This is a strong tool to reduce vulnerability, especially when rocking motion should be avoided and sliding motion is welcome, as in the case of artistic heritage. This paper focuses the attention on this last problem, common to a large class of both non-structural and structural elements that can lose their functionality because of earthquake motions. The results of a numerical modelling of sliding and rocking motion in presence of both different excitations and mechanical parameters are presented and compared with experimental data performed by the authors. The results developed are in good agreement with the laboratory tests and this assures the reliability of both the analytical procedure and the determination of the parameters involved. A model for a safeguard proposal is provided.

Dans de nombreuses cavites produites par l'erosion naturelle ou par l'activite humaine, le phenomene de chutes de blocs du plafond comporte de graves risques pour la securite, et donc pour l'utilisation de ces lieux a des fins d'activites humaines. Les auteurs ont deja propose une methode pour calculer, au moyen du theoreme de la limite superieure de la theorie de plasticite, la forme et les dimensions des blocs qui peuvent s'effondrer. Le materiau forme de roche molle a ete modelise au moyen du critere limite de Mohr-Coulomb, et la loi d'ecoulement associe a ete utilisee pour la vitesse de deformation plastique. Le critere limite de deformation elastique a ete convenablement regularise au moyen d'un cercle dans la zone de traction. La frontiere du bloc qui s'effondre est decrite par une surface paraboloide. Dans cet article, on formule une procedure d'optimisation dans la forme standard de Kuhn-Tucker et on obtient une solution analytique. L'algorithme mentionne ci-haut a ete applique avec succes a des sols frequemment rencontres dans le sud de l'Italie. Pour valider la formulation theorique, plusieurs essais numeriques ont ete effectues dans cet article. Ces essais montrent une concordance optimale avec la solution exacte mentionnee. En consequence, la modelisation proposee peut etre utilisee comme guide utile pour le calcul de confortement des cavites.