Search results for " aging."
showing 10 items of 556 documents
Redesign of the Geometry of Parts Produced from PBT Composite to Improve Their Operational Behavior
2021
Parts produced from PBT-GF30 (70% polybutylene terephthalate +30% fiberglass) are very often used in car construction, due to the properties of this material. The current trend is to make parts with a shape designed to be as complex as possible, to take over many functions in operation. During the research, a part that is a component of the structure of car safety systems, and that must be completely reliable in operation, was analyzed. This piece has a complex shape that involves the intersection of several walls. Thus, the research aimed at establishing the optimal radius of connection between the walls (R), the ratio between the thickness of the intersecting walls (K) and the angle of in…
Aging resistance of bio-epoxy jute-basalt hybrid composites as novel multilayer structures for cladding
2017
Abstract Aging resistance of jute reinforced laminates is compared with two jute/basalt hybrid laminates prepared with different stacking sequences (i.e., sandwich and intercalated configuration). To this aim, composites are exposed to cyclic conditions comprising hygrothermal stress and UV radiation to promote an accelerated aging, for a period of 84 days. Specimens of each laminate are tested after 14, 28, 56 and 84 days, respectively. Quasi-static flexural tests, Charpy impact tests and dynamic mechanical tests are performed according to international ASTM and ISO standards. Furthermore, scanning electron microscopy and differential scanning calorimetry are used to evaluate the morpholog…
Salt-fog spray aging of jute-basalt reinforced hybrid structures. Flexural and low velocity impact response
2017
Abstract In this work, a study on the aging resistance of jute and jute-basalt interply hybrid laminates exposed to salt-fog is presented with the aim to investigate the possibility to enhance the durability of natural fiber reinforced composites for marine application by a ply-substitution approach. In particular, jute and basalt/jute reinforced composite plates were manufactured by vacuum assisted resin infusion in two different staking sequences (i.e., intercalated and sandwich-like basalt-jute) and aged under salt fog conditions. The effects of the accelerated aging at increasing times on the mechanical response of laminates were assessed in both quasi static (three point bending) and d…
Investigation and modeling of the anomalous yield point phenomenon in pure tantalum
2014
International audience; The monotonic and cyclic behavior of commercially pure tantalum has been investigated at room temperature, in order to capture and understand the occurrence of the anomalous yield point phenomenon. Interrupted tests have been performed, with strain reversals (tensile or compressive loading) after an aging period. The stress drop is attributed to the interactions between dislocations and solute atoms (oxygen) and its macroscopic occurrence is not systematically observed. InfraRed Thermography (IRT) measurements supported by Scanning Electron Microscopy (SEM) pictures of the polished gauge length of a specimen during an interrupted tensile test reveal the nucleation an…
Service Life of Cementitious Photocatalytic Paints Newly Formulated
2013
The use of photocatalytic products for surface coating of buildings contributes to the sustainability of building interventions, due to the reduction of some atmospheric pollutants and self-cleaning attitude. The world market produces a wide range of coatings, applied in limited thickness, transparent and opaque, high initial performance, although data on their durability are still missing. The knowledge of the performance over time of such innovative products is necessary according to the new EU Regulation No. 305/2011, which introduced for construction works, the seventh requirement on their sustainability and particularly their durability. The study concerns the evaluation of the durabil…
An aging evaluation of the bearing performances of glass fiber composite laminate in salt spray fog environment
2019
The aim of the present paper is to assess the bearing performance evolution of pinned, glass-composite laminates due to environmental aging in salt-spray fog tests. Glass fibers/epoxy pinned laminates were exposed for up to 60 days in salt-spraying, foggy environmental conditions (according to ASTM B117 standard). In order to evaluate the relationship between mechanical failure mode and joint stability over increasing aging time, different single lap joints, measured by the changing hole diameter (D), laminate width (W) and hole free edge distance (E), were characterized at varying aging steps. Based on this approach, the property-structure relationship of glass-fibers/epoxy laminates was a…
Effects of weathering on the performance of self-cleaning photocatalytic paints
2019
Abstract The use of photocatalytic products for the surface coating of buildings is spreading more and more, because of the reduction of atmospheric pollutants and the colour maintenance of the paints over time with reduction of the maintenance costs and the improvement of the aesthetic appearance. The study reports the evaluation of the effects of the atmospheric conditions on three commercial photocatalytic paints containing TiO2. In particular tests were carried out by using samples subjected to accelerated aging inside a climate chamber and naturally aged by exposure for two years to the external environment of the city of Palermo (representative of a coastal environment of the Mediterr…
Effects of nutraceuticals of Mediterranean diet on aging and longevity
2020
Abstract Among the many existing dietary interventions, Mediterranean diet has received much attention because of its beneficial influence on healthy aging and longevity. Mediterranean dietary pattern, characterized by low glycemic index and low-animal protein intake, is rich in nutraceuticals and functional foods, and bioactive compounds able to reduce the signaling of molecular pathways, such as nutrient-sensing ones, affecting aging process. Therefore a close adherence to a Mediterranean-style diet allows avoiding cardiovascular disorders and other age-related diseases, and it is responsible for the high rate of long-living individuals scattered throughout the Mediterranean basin. For th…
Approaches to study yeast cell aging and death
2014
For millennia, yeast has been exploited to obtain fermentation products, such as foods and beverages. For c. 50 years, yeast has been an established model organism for basic and applied research, and more specifically, for c. 15 years, this unicellular organism has been applied to dissect molecular mechanisms of cell aging and programmed cell death. In this review, we present an overview of approaches to study cell aging and death in yeast, including lifespan assessments, calorie restriction, cell viability, survival, and death markers.
New Insights Into the Skin Microbial Communities and Skin Aging
2020
Although it is well-known that human skin aging is accompanied by an alteration in the skin microbiota, we know little about how the composition of these changes during the course of aging and the effects of age-related skin microbes on aging. Using 16S ribosomal DNA and internal transcribed spacer ribosomal DNA sequencing to profile the microbiomes of 160 skin samples from two anatomical sites, the cheek and the abdomen, on 80 individuals of varying ages, we developed age-related microbiota profiles for both intrinsic skin aging and photoaging to provide an improved understanding of the age-dependent variation in skin microbial composition. According to the landscape, the microbial composi…