More than a century has passed since pathological protein aggregates were first identified in the brains of patients with neurodegenerative diseases (NDDs). Yet, we still do not have effective ...therapies to treat or slow the progression of these devastating diseases or diagnostics for early detection and monitoring disease progression. Herein, I reflect on recent findings that are challenging traditional views about the composition, ultrastructural properties, and diversity of protein pathologies in the brain, their mechanisms of formation and how we investigate and model pathological aggregation processes in the laboratory today. This article is an invitation to embrace the complexity of proteinopathies as an essential step to understanding the molecular mechanisms underpinning NDDs and to advance translational research and drug discovery in NDDs.
The possibility of using recycled aggregates from construction and demolition waste (CDW) in concrete is rather widely agreed upon when it comes to the use of coarse recycled aggregates. However, ...this is not the case when fine recycled aggregates (FRA) are considered, as it is deemed that these seriously impair the behaviour of concrete. Hence, this work presents a technical specification proposal for the use of FRA from CDW in concrete, to attempt to fill this gap in legislation. The specification is based on a wide collection of experimental results, from which it is shown that for low incorporation ratios (up to 25%), the properties of concrete with FRA from CDW are comparable to those of a reference concrete. The intended international scope of the specification is ensured by the fact that FRA from CDW are typified by composition (percentage of concrete, masonry, glass, etc.) rather than by geographical origin or construction type. It is shown that, after typifying the FRA and assuming, as per design, the acceptable percentage losses (relative to a reference concrete) of mechanical, durability-related and long-term physical properties, if the maximum incorporation ratios proposed of each type of FRA are used, the variation of properties remains within the limits established.
•The effects of CRCA replacement level under the combined F–T and sulfate attack are analyzed.•The effects of LVFA and HVFA under the combined F–T and sulfate attack are analyzed.•The durability was ...more affected by the FA content than by the CRCA replacement level.•Interaction between F–T and sulfate attack to concrete with RCA and FA is discussed.•NMR and XRD analysis of concrete subjected to F–T cycles in sulfate solutions are conducted.
The present study investigated the effect of the combined action of freeze–thaw (F–T) cycles and sulfate attack on the resistance of concrete containing low-volume fly ash (LVFA) and high-volume fly ash (HVFA) made with coarse recycled concrete aggregates (CRCAs). Concretes with a water–binder ratio of 0.50 containing fly ash (FA; LVFA and HVFA) and CRCA (i.e., 0%, 20%, 50% and 100% also by weight) as a replacement for coarse natural aggregates (CNAs) were exposed to water, 5% sodium sulfate solution and 5% magnesium sulfate solution under F–T cycles. The performance, including residual compressive strength, relative dynamic modulus of elasticity and concrete microstructure, was evaluated after being subjected to certain F–T cycles in sulfate solutions. Results indicated that the resistance of the concrete mixtures to the combined F–T cycles and sulfate attack increased with the increase in CRCA content as CNA replacement. Compared with the concrete without FA, the LVFA-based concrete showed excellent improvement in the resistance to the combined action of F–T cycles and sulfate attack; however, the HVFA-based concrete had an adverse effect on the resistance. Concrete deterioration was attributed to the interaction between F–T and sulfate attack. Moreover, the resistance of LVFA- and HVFA-based concretes against the combined F–T and sulfate attack increased during the entire test when the concretes were subjected to F–T cycles in 5% sodium sulfate solution. The sulfate attack exerted more positive effects than negative on the F–T cycles. However, the resistance of LVFA- and HVFA-based concretes against the combined F–T and sulfate attack increased during the initial F–T cycles and then decreased in the 5% magnesium sulfate solution. The 5% sodium sulfate solution produced similar improvements in the F–T resistance of the LVFA- and HVFA-based concretes, whereas the 5% magnesium sulfate solution evidently reduced the F–T resistance of the concrete with HVFA than that with LVFA.
Novel hybrid binder concrete mixes with alkali-activated non-ferrous slag (NFS), either alone or in combination with blast furnace slag (BFS), as partial replacement of Portland cement, and ...containing 50% recycled aggregates, were successfully manufactured. The compressive strength, carbonation resistance, chloride resistance, frost scaling, sorptivity coefficient, and water penetration resistance were thoroughly assessed. The presence of recycled aggregates had an adverse effect on early-age strength, but after 91 days there was no difference between concrete with and without recycled aggregates. The chloride-binding capacity was enhanced in the BFS/NFS system with recycled aggregates (reduction in chloride ingress coefficients of ~28–35% compared to recycled concrete with NFS only). This is most likely caused by the binding of Cl ions in calcium alumina silicate hydrates (C-A-S-H) and ettringite phases. However, when compared to the system with virgin aggregates, BFS/NFS concrete with recycled aggregates showed increased carbonation rate (+30%) and frost scaling (+15%). Durability properties, such as sorptivity and water penetration resistance, were positively affected by the curing time for the BFS/NFS system (~35–45% further improvement from 28 to 90 days with respect to the NFS system). Specimens that were wet cured for 91 days showed improved results compared to the 28-day cured samples due to the slow pozzolanic reaction of the NFS.
It is of great significance to develop new types of refractories by replacing the traditional refractory aggregate with a porous refractory aggregate, which enables the long-lived operation of ...high-temperature industries and low carbon emissions. In this study, microporous MgAl2O4 aggregates containing sub-micron pores were successfully prepared from magnesite and boehmite using an in-situ decomposition pore-forming method. The effects of sintering temperature on the phase compositions, sintering properties, and microstructure of the aggregates were reported for the first time. The resulting aggregates sintered at 1500 °C showed superior comprehensive performance with a median equivalent pore diameter of 10.75 μm, corresponding to a bulk density and closed porosity of 2.27 g cm−3 and 8.7%, respectively. Meanwhile, several sub-micron pores were observed in microporous MgAl2O4 aggregates, which contributed to a lower thermal conductivity of 1.932 W m−1 k−1 at 500 °C and a higher compressive strength of 40.8 MPa. In addition, the formation mechanism of sub-micron pores was proposed, and the effects of pore structure on the thermal conductivity and compressive strength were discussed.
We propose a new type of concrete for the attenuation of elastic waves induced by dynamic excitation. In this metamaterial, which we call metaconcrete, the stone, sand, and gravel aggregates of ...standard concrete are replaced with spherical inclusions consisting of a heavy metal core coated with a soft outer layer. These engineered aggregates can be tuned so that particular frequencies of a propagating blast wave will activate resonant oscillations of the heavy mass within the inclusions. The resonant behavior causes the system to exhibit negative effective mass, and this interaction between the wave motion and the resonant aggregates results in the attenuation of the applied dynamic loading. We introduce the concept of negative mass by deriving the effective momentum mass for the system and we define the geometrical and material parameters for the design of resonant aggregates. We develop finite element models for the analysis of metaconcrete behavior, defining a section of slab containing a periodic arrangement of inclusions. By computing the energy histories for the system when subject to a blast load, we show that there is a transfer of energy between the inclusions and the surrounding mortar. The inclusions are able to absorb a significant portion of the applied energy, resulting in a reduction in the amount of stress carried by the mortar phase and greatly improving the ability of the material to resist damage under explosive dynamic loading.
The construction sector is one of the most energy-intensive and raw-material-demanding human activities and, hence, contributes a significant share of greenhouse gas emissions. As a matter of ...principle, making the construction sector “greener” is one of the main challenges for policy makers, private companies and the scientific community. For this reason, one of the most promising actions is based on recycling Construction and Demolition Waste (CDW) and converting them into secondary raw materials for the construction sector itself. Moreover, the reduction of the environmental impact can be further amplified through the optimization of the production, assembly and deconstruction/reuse procedures and through the maximization of the service life. In this aim, the present work aims at analyzing the environmental performance of duly sized and designed prefabricated Decontructable and Reusable Beam (DRB) incorporating with Recycled Concrete Aggregates (RCA) assembled by means of an innovative system based on a memory®-steel prestressing technique. The environmental performance is evaluated through Life Cycle Assessment with a cradle-to-gate approach: the analysis of 16 midpoint impact categories was conducted using the methodology proposed by EN15804. In this context, three allocation scenarios for avoided impacts due to reuse (100-0, 50:50 and 0-100) were considered, and a sensitivity analysis was performed. It was verified that due to the higher amount of post-tensioning required for the innovative shape memory alloy steel bars, the DRBs present inferior environmental performance than the Ordinary Beams (ORB). However, when analyzing the reuse scenarios, it was observed that the DRB could have considerably lower impacts, depending on the type of allocation procedure adopted in LCA modeling. This study brings as the main contribution an evaluation and some design guidelines for the development of circular concrete structures based on the principles of Design for Deconstruction (DfD) and the prefabricated process.
Neurodegeneration in Alzheimer's disease (AD) is closely associated with the accumulation of pathologic tau aggregates in the form of neurofibrillary tangles. We found that a p.Asp395Gly mutation in
...(valosin-containing protein) was associated with dementia characterized neuropathologically by neuronal vacuoles and neurofibrillary tangles. Moreover, VCP appeared to exhibit tau disaggregase activity in vitro, which was impaired by the p.Asp395Gly mutation. Additionally, intracerebral microinjection of pathologic tau led to increased tau aggregates in mice in which p.Asp395Gly
mice was knocked in, as compared with injected wild-type mice. These findings suggest that p.Asp395Gly
is an autosomal-dominant genetic mutation associated with neurofibrillary degeneration in part owing to reduced tau disaggregation, raising the possibility that VCP may represent a therapeutic target for the treatment of AD.
Phthalocyanine (Pc) molecules exhibit high extinction coefficients in near-infrared region, rendering them well-suited for phototherapies, but most of their applications are limited to the field of ...photodynamic therapy (PDT). Herein, for the first time, we illustrate that Pc molecules can be endowed with excellent photothermal properties by means of structural regulation rather than formation of aggregates. Three representative Pc derivatives show efficient activities of photothermal therapy (PTT) against human hepatocellular carcinoma cells. Among them, copper phthalocyanine (PcC1) exhibits a high
PTT efficacy against mice bearing S180 tumors. The unique investigation in this article should light up a perspective of Pc's new applications for PTT, which enable to make up the inherent defects of PDT.
•The elevated-temperature thermal conductivity, specific heat and thermal expansion of coarse RCA concrete are studied.•The effects of temperature and coarse RCA content on the elevated-temperature ...thermal properties are analyzed.•The relationships to model the elevated-temperature thermal properties of coarse RCA concrete are suggested.
An experimental investigation was carried out on the thermal properties of concrete made with coarse recycled concrete aggregate (RCA) in the temperature range from room temperature to 800 °C. Three different concrete mixtures were produced with replacement percentages of 0%, 50% and 100% coarse RCA. The thermal properties at elevated temperatures, including thermal conductivity, specific heat and thermal expansion were obtained from the tests. Test results in this paper show that the thermal conductivity of coarse RCA concrete decreases with increasing coarse RCA content. The development trends of thermal conductivity and specific heat with temperature are similar among concretes with different coarse RCA content. For thermal expansion, the concrete with 50% coarse RCA has a larger value than the concrete containing 0% and 100% coarse RCA at temperatures above 500 °C. Based on the test data, simplified equations were proposed to express the elevated-temperature thermal properties of coarse RCA concrete.
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