39 research outputs found
Durability of reclaimed asphalt pavement–coal fly ash–carbide lime blends under severe environmental conditions
The sustainable use of industrial residue in enhancing the long-term performance of reclaimed asphalt pavement (RAP) has been proven to be effective under freeze–thaw and wet–dry conditions. This study focuses on coal fly ash (FA) and carbide lime (CL) as the enhancing agents. It evaluates how the durability and long-term performance of compacted RAP–FA–CL mixtures are impacted by dry unit weight and lime content. The tested mixture’s specimens were moulded in three layers through static compaction inside a cylindrical mould. Several single-level variables were used in the stabilisation process. Among these were: FA content of 25%, optimum water content of 9% (modified effort) and seven days of curing. Additionally, three target dry unit weights (17, 18 and 19 kN/m3 – the last of which was determined using the modified Proctor energy) and three percentages of lime content (3%, 5% and 7%) were used for a comparative analysis. The tested specimens’ accumulated loss of mass (after wetting–drying and freezing–thawing cycles) and splitting tensile strength were both evaluated as a function of the porosity/lime index. The experiments revealed that compacted RAP–coal FA–CL mixtures performed noticeably worse when subjected to freezing–thawing cycles than when subjected to wetting–drying cycles. These results indicate an increase in the breadth of the porosity/lime index, as it is shown to control the long-term performance of compacted RAP–coal FA–CL mixtures, in addition to controlling their mechanical response
Endoparasites in domestic animals surrounding an Atlantic Forest remnant, in São Paulo State, Brazil
Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases
The production of peroxide and superoxide is an inevitable consequence of
aerobic metabolism, and while these particular "reactive oxygen species" (ROSs)
can exhibit a number of biological effects, they are not of themselves
excessively reactive and thus they are not especially damaging at physiological
concentrations. However, their reactions with poorly liganded iron species can
lead to the catalytic production of the very reactive and dangerous hydroxyl
radical, which is exceptionally damaging, and a major cause of chronic
inflammation. We review the considerable and wide-ranging evidence for the
involvement of this combination of (su)peroxide and poorly liganded iron in a
large number of physiological and indeed pathological processes and
inflammatory disorders, especially those involving the progressive degradation
of cellular and organismal performance. These diseases share a great many
similarities and thus might be considered to have a common cause (i.e.
iron-catalysed free radical and especially hydroxyl radical generation). The
studies reviewed include those focused on a series of cardiovascular, metabolic
and neurological diseases, where iron can be found at the sites of plaques and
lesions, as well as studies showing the significance of iron to aging and
longevity. The effective chelation of iron by natural or synthetic ligands is
thus of major physiological (and potentially therapeutic) importance. As
systems properties, we need to recognise that physiological observables have
multiple molecular causes, and studying them in isolation leads to inconsistent
patterns of apparent causality when it is the simultaneous combination of
multiple factors that is responsible. This explains, for instance, the
decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference