Mechanical qualification of collagen membranes used in dentistry

The aim of this work is the qualification of commercially available collagen membranes in a comparative manner. The natural origin of collagen makes standardization difficult. Nevertheless, through dimensional and mechanical measures it is possible to mechanically qualify collagen membranes, and compare them.METHODS:Three commercially available collagen membranes used in Guided Bone Regeneration (GBR) and in Guided Tissue Regeneration (GTR) techniques, namely Bio-Gide, Collprotect and Jason, were chosen for the comparison. Quasi-static (tensile tests) and time-dependent (stress relaxation test) mechanical tests together with a functional test (tear test) were done to determine the responses of collagen membranes under different loading conditions. RESULTS: The tested membranes exhibited different behaviours, different deformability values and thickness, Jason being the thinnest and Bio-Gide the thickest. Similar differences were also observed in terms of surface density. DISCUSSION: Even though clinical observations were not within the aim of this study, our findings indicate that a better understanding of the correlation between mechanical properties and thickness could lead to a more rational design and use of these membranes in the face of specific clinical cases

Micro-Raman investigation of coloured glazes on majolica sherds from the Monk’s Palace waste shaft in Capena (Rome)

Medieval and Renaissance waste shafts (butti) offer a unique opportunity to study objects of common use in the past, the majority of findings that emerge from the excavation of these pits are pottery found in fragmentary condition, sherds that provide essential information on the historical periods to which the butto belongs. In the present work Micro-Raman analysis was conducted on a representative group of samples dated back from XIV to XVIII century, coming from the waste shaft pertained to the Monk’s Palace sited in Leprignano, the current Capena in the province of Rome. The aim of the study was to characterize the composition of coloured glazes pertaining to majolica sherds, through a technique that has proved to be invaluable for this purpose, according to the amount of published data in recent years. Differences in terms of structure and constituents of the decorative layers have been observed. Yellow pigments can be ascribed to the family of lead pyroantimonates, in both binary and ternary form, brown and green glazes are constituted by ions dissolved in the glass matrix, while in blue glazes cobalt olivines have been clearly identified for some samples. Polymerization index calculated on vitreous layers shows the presence of a lead-based glaze that is commonly found in majolica referable to the same age and provenance. The results obtained are in a good agreement with Piccolpasso’s treatise, “The Three Books of Potter's Art”, except for a sherd pertaining to a later Ligurian production

Shape Memory Composites for Self-deployable Structures in Aerospace Applications

AbstractShape memory composites (SMCs) are attractive materials as they combine typical mechanical and functional properties of composites with shape memory properties. Such properties can be given to composite materials and structures by using shape memory polymer (SMP) matrices or integrating parts made of SMPs. In the case of integration, flexible composite skins can be applied over a shape memory foam core obtaining composite sandwich that can be shaped to change its stiffness or to reduce its volume. After the application of a given stimulus (generally by heating) the initial shape can be recovered. Future applications for this class of materials are self-deployable structures for space systems (such as actuators of solar sails or smart aerodynamic structures). In this work, two new SMC self-deployable structures were prototyped: a composite cross and a composite frame containing a thin aluminum sheet. The former structure represents a possible deploying configuration for a structural sheet whereas the latter is a conceptual study of a solar sail. The experimental results are very promising, showing that such structures can successfully self-deploy following the desired design constraints without noticeable damages. Finally, new perspectives for applications are highlighte

Cold Compression Molding of Pyrolytic Carbon from Tires for Oil Absorbers

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surface tailoring of aluminum sheets by pvd sputtering

Abstract In order to change surface morphology of aluminum sheets, they have been mounted as targets in a PVD sputtering system, and subjected to several sputtering cycles. As an effect of the plasma erosion, sheet surface continuously changes during multiple sputtering cycles. First results are shown in terms of surface morphology. The levelling effect of the plasma erosion is evident as initial irregularities from rolling partially disappear, and surface profiles become smoother by increasing number of cycles. That is the first result in the direction of surface tailoring, and nano-grooves could be expected at very high numbers of cycles. Surface nano-tailoring would be the first step for the production of patterns in injection molding of common polymers

GPR activities in Italy: a review

Ground-penetrating radar has been increasingly played an important role over the last 15 years in Italy due to its high reliability in assisting the assessment of the built environment for civil engineering purposes, and in being used for geophysical investigations within many other fields of application. In line with this, original works involving fundamental aspects of this technique and implementing its use more practically in a number of interesting projects have been developed over years, both under a research and an enterprise point of view. This paper will endeavour to review the current status of ground-penetrating radar activities in Italy. Efforts have been devoted to single out the most interesting national research projects, both recent and ongoing, involving ground-penetrating radar in Italy, such as the ARCHEO project in the 90s, funded by the Italian Ministry for Universities, wherein a stepped frequency ultra-wide band radar suited for archaeological surveys was manufactured. In this framework, it is worth citing another important and more recent project, European Community funded, namely, ORFEUS, which started in the late 2006 with the overall aim of providing the capability to locate buried infrastructure accurately and reliably by means of a bore-head ground-penetrating radar for horizontal directional drilling. A review on the main use of this non-destructive technique in management activities of national resources and infrastructures has been also performed, ranging from the applications made by Anas S.p.A., i.e. the main management authority for the Italian road and motorway network, up to private enterprises specialized in both services providing and ground-penetrating radar manufacturing such as, to cite a few, Sineco S.p.A. and IDS Ingegneria dei Sistemi S.p.A., respectively. Current national guidelines, rules or protocols to be followed during radar surveys have been also reviewed. Unlike well-established international standards such as the ASTM D 4748-98 and the ASTM D 6432-99 dealing with, respectively, thicknesses evaluation of bound layers in road pavements, and equipment, field procedures and data-interpretation for the electromagnetic evaluation of subsurface materials, it has to be noted that the Italian body of laws and rules tackles the ground-penetrating radar applications under an indirect and partial approach. Despite of such situation, national guidelines concerning utilities-detection activities as well as other theoretical and practical guidelines established by the major Italian private enterprises on this field can be also considered highly relevant. Moreover, a further focus on the activities and main devices of the major Italian ground-penetrating radar manufacturers have been thoroughly described. Under a research and innovation perspective, the most important test sites, such as the site of the University of Salento to reconstruct archaeological and urban subsurface scenarios have been listed along with the main advances reached in integrating ground-penetrating radar with other non-destructive techniques, to inform and potentially improve the possibility of new developments and collaborations

Materials International Space Station Experiment-9 (MISSE-9) Polymers and Composites Experiment

Spacecraft in low Earth orbit (LEO) are subjected to harsh environmental conditions, including radiation (cosmic rays, ultraviolet, x-ray, and charged particle radiation), micrometeoroids and orbital debris, temperature extremes, thermal cycling, and atomic oxygen (AO). These environmental exposures can result in erosion, embrittlement and optical property degradation, threatening spacecraft performance and durability. To increase our understanding of effects such as AO erosion and radiation induced embrittlement of spacecraft materials, NASA Glenn has developed a series of experiments flown as part of the Materials International Space Station Experiment (MISSE) missions on the exterior of the International Space Station (ISS). These experiments have provided critical LEO space environment durability data such as AO erosion data for many materials and mechanical properties changes after long term space exposure. In continuing these studies, a new experiment called the Polymers and Composites Experiment has been selected for flight on the MISSE-Flight Facility (MISSE-FF). The Polymers and Composites Experiment will be flown as part of the MISSE-9 mission, the inaugural mission of MISSE-FF manifested on SpaceX-14. This experiment includes 138 samples being flown in ram, wake or zenith orientations for space environmental durability assessment. The primary objective is to determine the LEO AO erosion yield, Ey (the volume loss per incident oxygen atom (cm3/atom)), of polymers, composites, and coated samples, as a function of solar irradiation and AO fluence. In addition, epoxy samples with varying levels of ZnO powder are included to study the effect of filler quantity on AO erosion. An AO Scattering Chamber is included to help improve the understanding of AO scattering mechanisms for improved AO undercutting modeling. Indium tin oxide (ITO) coated samples are included to validate the durability of ITO conductive coatings in LEO. Tensile samples of Teflon fluorinated ethylene propylene (FEP) of varying thicknesses and back-surface coatings will be flown in wake and zenith orientations to study radiation embrittlement versus thickness, and the effect of heating on FEP embrittlement. Finally, shape memory composite and cosmic ray shielding samples will be flown for LEO durability assessment. This paper presents an overview of the MISSE-9 Polymers and Composites Experiment

Circulating resistin levels and risk of multiple myeloma in three prospective cohorts

BACKGROUND: Resistin is a polypeptide hormone secreted by adipose tissue. A prior hospital-based case-control study reported serum resistin levels to be inversely associated with risk of multiple myeloma (MM). To date, this association has not been investigated prospectively. METHODS: We measured resistin concentrations for pre-diagnosis peripheral blood samples from 178 MM cases and 358 individually matched controls from three cohorts participating in the MM cohort consortium. RESULTS: In overall analyses, higher resistin levels were weakly associated with reduced MM risk. For men, we observed a statistically significant inverse association between resistin levels and MM (odds ratio, 0.44; 95% confidence interval (CI) 0.24-0.83 and 0.54; 95% CI 0.29-0.99, for the third and fourth quartiles, respectively, vs the lowest quartile; Ptrend=0.03). No association was observed for women. CONCLUSIONS: This study provides the first prospective evidence that low circulating resistin levels may be associated with an increased risk of MM, particularly for men

Mechanical qualification of collagen membranes used in dentistry

Aim. The aim of this work is the qualification of commercially available collagen membranes in a comparative manner. The natural origin of collagen makes standardization difficult. Nevertheless, through dimensional and mechanical measures it is possible to mechanically qualify collagen embranes, and compare them. Methods. Three commercially available collagen membranes used in Guided Bone Regeneration (GBR) and in Guided Tissue Regeneration (GTR) techniques, namely Bio-Gide, Collprotect and Jason, were chosen for the comparison. Quasi-static (tensile tests) and time-dependent (stress relaxation test) mechanical tests together with a functional test (tear test) were done to determine the responses of collagen membranes under different loading conditions. Results. The tested membranes exhibited different behaviours, different deformability values and thickness, Jason being the thinnest and Bio-Gide the thickest. Similar differences were also observed in terms of surface density. Discussion. Even though clinical observations were not within the aim of this study, our findings indicate that a better understanding of the correlation between mechanical properties and thickness could lead to a more rational design and use of these membranes in the face of specific clinical cases