323,012 research outputs found
Flexible packaging structures for high pressure treatments
No full textThis paper reviews the possible effects determined on polymeric food packaging films by the simultaneous application of pressure (P) and temperature (T) in high pressure pasteurization and sterilization treatments of packaged foodstuffs. Both theoretical modelling and experimental issues are discussed. In fact reversible and irreversible effects that could occur in single film as well as in multilayer film structures have been reviewed and correlated to the variation of structural andmorphological properties of the polymeric materials, under P/T conditions relevant for the specific application. The structural changes of the amorphous and crystalline domains of polymer films could
possibly occur in response to pressure and/or temperature conditions, which, in turn, result in detectable effects on
properties of packagingmaterials. Particular attention has been devoted to addressing issues like irreversible alteration
of functional (i.e., barrier to gases and water vapor, scalping and migration phenomena) and mechanical properties
of the packaging materials in a relationship with a modification of degree of crystallinity, aging of the amorphous phase, delamination of multilayer films, rubbery to glassy state transition promoted by pressure and plasticization induced by absorption of low molecular weight compounds.
Industrial relevance: High pressure processing (HPP) is steadily gaining as a food preservationmethod that preserves natural sensory and nutritional attributes of food with a minimal quality loss. In fact, packaged foods processed by using this technique maintain most of their original texture and nutritional qualities, additionally exhibiting an extended shelf-life.
Industrially, the selection of the proper polymeric materials as well as the packaging structure becomes extremely importantwhen both high pressure and high temperature are employed for high pressure sterilization processes. In this context, an important issue that is relevant for industrial applications is to predict the possible effects of treatments
on the structure and morphology of thematerials which, in turn, can determine relevant effects on mechanical, functional (i.e., gas and vapor barrier properties) and aesthetic (e.g., see-through clarity) properties. In fact, modification of the crystallinity level, density change of amorphous regions and possible hydrolysis phenomena could hamper the use of the packaging material for the HPP applications. Moreover, multilayer flexible films can, in some cases, display delamination phenomena leading to unacceptable modifications of the aspect as well as of the integrity of the packaging structure
Microstructural and micromechanical study of a Ti6Al4V component made by electron beam melting
No full textAdditive Layer Manufacturing is one of the most promising and investigated manufacturing system due to its advantages to produces near net shape components, also with a very complex shape, in a single shot. Among the different techniques now available, the Electron Beam Melting (EBM) is of particular interest in the production of metal components. Particularly the application of this technique to titanium alloys allows to produces components with a very low buy to fly ratio. In the present paper the microstructure attained is accurately described and mini tensile tests performed allowed to understand the fracture behavior of specimen with the specific microstructure realized under static load. © 2016 Author(s)
Tensile properties of AA6156-T4 friction stir welded joints in as-welded and post-weld aged condition
No full textThe effect of the T62 post-weld heat treatment on the tensile strength of AA6156-T4 friction stir welded joints is studied. To this aim, the 0.2% proof stress and the tensile strength of as-welded and post-weld treated joints as function of the rotating and welding speed was analyzed performing a complete factorial design with three levels for each studied parameter. Statistical analyses were carried out to establish empirical models of the tensile prop-erties of the joints as a function of the studied welding parameters. The obtained models were validated through statistical tools such as Mallow's CP, S, & R2 and R2 (adj). The developed regression models can be effectively used to predict the mechanical proprieties of the joints at 95% confidence level
MYCOPLASMA FERMENTANS, MYCOPLASMA HOMINIS, UREAPLASMA UREALYTICUM IN ASSOCIAZIONE ALLE INFEZIONI BATTERICHE NELLE PATOLOGIE GENITALI
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Chemical Machining of Copper-Based Aerospace Alloys Produced Through Additive Manufacturing: A Preliminary Approach to Improve Surface Quality
No full textAdditive Manufacturing (AM) is transforming the production of high-performance components, particularly in the aerospace sector. However, the surface quality of AM products often does not meet industry standards, necessitating additional treatments. Chemical machining processes are especially advantageous for preserving the intricate geometries of AM parts, yet their application can be challenging for certain metals due to the presence of alloying elements. The objective of this study is to evaluate the enhancement of surface properties, with a focus on roughness reduction, in GRCop-42 components fabricated via powder bed fusion technology, through the application of chemical machining treatments. Two distinct chemical machining solutions were considered: one formulated with ferric chloride and the other composed of a mixture of sulfuric and nitric acids. Furthermore, two experimental setups were implemented to assess the efficacy of ultrasound assistance during the chemical machining process. The results demonstrated that both chemical solutions effectively removed surface material, with the integration of ultrasound significantly accelerating the process. Surface roughness was reduced by up to 13 pct and the steepness of the surfaces was markedly decreased, achieving a nearly uniform finish. However, the utilization of ultrasound with the lower viscosity solution resulted in cavitation erosion, which created undesirable cavities on the surface
Caratterizzazione igienistica delle acque del fiume Sarno: evoluzione della qualità chimica e microbiologica
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Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
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