2,235 research outputs found
CD30, Th2 cytokines and HIV infection: a complex and fashinating link
No full textCD30 is a member of the tumor necrosis factor (TNF)/nerve growth factor (NGF) receptor superfamily, and was originally described as a marker of Hodgkin's and Reed-Sternberg cells in Hodgkin's lymphoma. CD30 is preferentially expressed on CD4+ and CD8+ T-cell clones that produce T helper 2 (Th2)-type cytokines, and is also released in a soluble form by these cells. Elevated serum levels of soluble (s)CD30 have been found in some conditions in which a pathogenic role for Th2 cells has been suggested, such as atopy, Omenn's syndrome, systemic lupus erythematosus, as well as following infection with measles virus or human immuno-deficiency virus (HIV). Here, Gianfranco Del Prete and colleagues suggest a complex and fascinating link between the expression and release of CD30, and the immunopathogenesis of HIV infection
A physically based constitutive model of microstructural evolution of Ti6Al4V hard machining under different lubri-cooling conditions
No full textThe metallurgical phenomena taking place during machining processes affect the thermo-mechanical properties of the severely deformed materials, influencing, consequently, the process behavior. The microstructural modifications are difficult to be evaluated when the material is subjected to high speed deformations that are typical of material removal processes. Therefore, the microstructure-based numerical simulations can represent a useful tool able to properly predict their mechanics. Hard turning experiments were conducted on Ti6Al4V alloy, involving different process parameters and lubri-cooling conditions. The worked samples surfaces were assessed in terms of resulting microstructural changes and microhardness. The obtained results (cutting forces, temperature, and surface metallurgical modifications) were considered to develop and validate a physics-based model able to describe the microstructural phenomena occurring under large deformation processes, taking into account the influence of the physical phenomena that accommodate the material plastic strengthening and their resulting effects on the process variables. The dislocations reciprocal influence and their interaction with the material lattice were considered to understand the material viscoplastic flow. Moreover, also the recrystallization phenomena influencing the grain size related strengthening were considered to formulate the model. Then, the developed material model was implemented via user sub-routine in a commercial finite element (FE) software. The FE model was used to in-depth analyze the inner evolution of the processed material and to predict the variables of industrial interest. A good agreement was shown between the experimentally measured variables and the numerically predicted results. Moreover, the model was employed to investigate additional machining conditions via finite element analysis (FEA), demonstrating a huge capability to improve the manufacturing process performances, leading to a deeper knowledge of microstructural evolution and the material machinability under various process conditions
Advanced finite element model for predicting surface integrity in high-speed turning of AA7075-T6 under dry and cryogenic conditions
No full textL’influenza dei fenomeni franosi sugli insediamenti costieri del distretto flegreo (Campania, Italia)
No full textDirezione e forme organizzative dell'internazionalizzazione delle banche italiane: un'analisi panel
No full textDirezione e forme organizzative dell'internazionalizzazione delle banche italiane: un'analisi panel
No full textPrimo contributo sui sinkholes di origine naturale in Campania. Atti del Conv. � Stato dell�arte sullo studio dei fenomeni di sinkholes e ruolo delle amministrazioni statali locali nel governo del territorio� Roma 20-21 maggio, APAT, 361-376.
No full textViene presentata una prima sintesi sui fenomeni da sprofondamento di origine naturale “sinkholes” che hanno interessato la Campania. Essi interessano sia rocce (calcari mesozoici) che terreni sciolti ed a granulometria variabile (dal detrito di falda alle ghiaie di conoide, a depositi alluvionali limo sabbiosi, a depositi piroclastici incoerenti o poco coerenti). Le prime analisi hanno permesso di constatare che i sinkhole si sviluppano, generalmente, lungo linee di faglia localizzate alla base di massicci carbonatici e, molto probabilmente, ancora attive. In quasi tutte le aree interessate dagli sprofondamenti sono presenti emergenze di falde mineralizzate. Si evidenzia, quindi, la stretta relazione tra tettonica recente, falde minerazate, fenomeni di ipercarsismo e genesi dei sinkhole
Il Partito comunista italiano dinanzi al processo alla Resistenza: il Comitato di Solidarietà Democratica e la difesa degli ex-partigiani (1948-1953)
No full textAn overview of the geological and morphological constraints in the excavation of artificial cavities
No full textThe habit of man to excavate artificial cavities began a very long time ago. Man’s efforts were initially moved by the need
to have a safe place to live, to control the surrounding territory, to collect and transport water, to exploit the natural
resources. For all these purposes, he had to face a number of geological and morphological constraints that, depending on
site characteristics, guided, favored or complicated the excavation. Therefore, all the phases in the “life” of an artificial
cavity, from the original idea, to planning and realization, up to its later evolution and possible conservation, depend in
some ways on geology and morphology. Lithology of hosting rock is the first aspect to consider: the rock mass must allow
hand excavation but, at the same time, it should present physical-mechanical characteristics such to support the newlyformed
cavity. The geological and structural setting, including the main faults and the discontinuity systems in the rock
mass, have to be particularly taken into account. Choice of the site where to locate an artificial cavity is also dictated by
morphology, the morphological factors being, in turn, strictly related to land management and control. When safety reasons
were considered to be the main priority, for instance, those sites that apparently were extremely difficult to excavate and
to settle in were chosen. Morphology is also strictly related to slope instability. Several rock settlements situated at the
borders of deep valleys and ravines are directly involved in mass movements, due to natural evolution of the slopes and
to open cracks produced by the tensional release in the unsupported rock mass. Inside the artificial cavities, in turn,
problems of instability may be observed. Locally, these may become so significant to compromise the overall stability of
the structure. Slope instability processes deserve a greater attention from cavers and scientists, since their effects might be
extremely dangerous for people visiting and working in artificial cavities, and for the cultural heritage therein contained
as well. Availability of water resources is a further factor that controlled during historical times the choice of sites for
settlements and towns. As a consequence, the hydrogeology plays a crucial role for artificial cavities, and particularly for
those works intended to collect and transport water to settlers and inhabitants. Aqueducts, tunnels, fountains are, for the
reasons above, very important to study in the context of the geological and hydrogeological setting, considering at the
same time the social and historical aspects of the community that designed and realized them. The present contribution is
an attempt in categorizing the aforementioned factors that play a role in the realization of artificial cavities. The topic is
very wide, covering several interrelated disciplines and field of research, and should deserve to be treated with much
greater detail and thoroughness. Our goal is therefore to stimulate with this article cavers and interested scientists in
carrying out studies about the crucial role that geology and morphology have in the development of artificial cavitie
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