1,721,004 research outputs found
Thermal insulation performance optimization of hollow bricks made up of 3D printable rubber-cement mortars. Material properties and FEM-based modelling
Full text linkSustainable construction is attracting more attention lately. It involves the design of eco-friendly building structures, the reduction of energy consumption and waste, the use of renewable and recyclable resources, and the enhancement of low-impact manufacturing methods. This paper addresses some of these sustainability questions, in the context of the use of tire recycled rubber particles as aggregates of cement mortars suitable for Additive Manufacturing (AM) processes. Specifically, the effect of rubber aggregates on physical and thermal properties was investigated, to evaluate the heat-insulating performance of the compounds. The lightweight and non-polar nature of rubber improve the thermal insulation and physical-structural properties of the material, in terms of thermal conductivity, unit weight, and porosity respectively. However, these effects are closely related to the particle size and their adhesion with the cement matrix. In the second part of the manuscript, applicability study of rubber-cement compounds based on the design and finite element method (FEM)-based thermal analysis of innovative hollow bricks is presented. Fractal cavities were investigated as a functional inner architecture to improve the thermal behavior of the component. FEM results show an increase of more than 30% in thermal resistance (RT) for fractal-based brick compared to conventional designs, demonstrating that the holes' geometric irregularity is a key feature in the thermal flow attenuation
Waste management of wind turbine blades: a comprehensive review on available recycling technologies with a focus on overcoming potential environmental hazards caused by microplastic production
Full text linkThe 2020 targets for sustainable development and circular economy encourage global leaders and countries to legislate laws and policies on several critical hot topics to prevent further global warming: (1) the increased utilization of renewable electrical power (wind turbine implants, as an example); (2) waste transformation into high-added-value materials based on the European Green Deal for energy transition; and (3) material and energy recovery and circularity. Accordingly, scholars and researchers have predicted that, hopefully, installed wind power capacity is going to increase dramatically by 2050. However, our ecosystem will have to face and deal with an enormous amount of decommissioned turbine blades. The disposal of these wastes via conventional methods could not only raise the possibility of microplastic formation, but could also boost the probability of environmental issues such as air pollution, soil, water contamination, etc. Moreover, these hazards will endanger wildlife and humans. As a result, the waste management of these retired blades composed of multi-lateral composite materials through a sustainable, effective, and feasible single/or hybrid process is necessary. This review aims to summarize all of the information about turbines, introduce all the various recycling pathways used for their blades, and provide a comparative analysis of these methods as well. In addition, the paper defines the possibility of microplastic formation from this waste (especially end-of-life turbine blade scraps), points out potential risks for the Earth, and suggests actions to inhibit their build-up and to keep the environment safe
Editorial: Knocking on neuroimmunology's doors: an entrechat concerning the immune system balance and its cell metabolism orchestration
No full textReducing the emission of climate-altering substances in cementitious materials. A comparison between alkali-activated materials and Portland cement-based composites incorporating recycled tire rubber
Full text linkLow carbon or near-zero carbon concrete technology is in line with the pillars of sustainable development, where industrial waste or low-carbon binders can reduce or eliminate consumption of Portland cement and natural resources, leading to less environmental pollution. This work presents an experimental study on the comparison between alkali-activated materials (also recognized as geopolymers) and a traditional cementitious matrix (Portland cement) incorporated with rubber particles, deriving from end-of-life tires, as replacement of raw mineral aggregates. To explore the potential of rubber-geopolymer compounds, an experimental comparative analysis with rubber-Portland mortars was performed. Initial investigations (microstructural/compositional analysis, porosity and water absorption measurements, and mechanical tests) were conducted on rubberized samples obtained by varying the binder, the sand-rubber replacement ratio (0 vol%, 50 vol%, and 100 vol%) and the rubber particle size (0–1 mm rubber fine aggregate and 1–3 mm rubber granules). The results revealed a greater compatibility of the alkali-activated matrix with tire rubber aggregates, resulting in better performance in terms of interfacial adhesion, reduced porosity rate, flexural strength, and toughness. However, compressive strength results showed a weaker mechanical performance of rubber-geopolymer mixes compared to Portland counterparts. As also verified by Si/Al elemental analysis, the structural quality and mechanical development of the geopolymer matrix was strongly influenced by the removal of sand as a Si-source. The potential embodied carbon emission performance and cost analysis were also estimated to evaluate the economic and environmental impact related to the use of recycled rubber as complete aggregate in Portland and geopolymer mixes. Sustainability analysis revealed the greater environmental friendliness of geopolymer formulations compared to those in ordinary cement, but higher production costs. The total addition of rubber aggregates induced an increase in emissions and costs (variable according to the type of matrix) which, however, does not directly correlate with the processing/price of the polymer fraction. Deepening the research on cleaner matrices and promoting the use of recycled materials in concrete applications could lead to a gap levelling between Portland and geopolymer rubber-based composites. Building on these findings, future study will focus on the optimization of the mix design as a function of rubber aggregates
Increased Foxp3(+) Regulatory T Cells in Poly(ADP-Ribose) Polymerase-1 Deficiency
No full textGrowing evidence is unveiling a role for poly(ADP-ribose) polymerase (PARP)-1 in the regulation of inflammatory/immune responses. In the current study, we investigated the effects of PARP-1 deficiency on regulatory T cell differentiation. Increased numbers of regulatory CD4(+)CD25(+)/Foxp3(+) T cells were found in thymus, spleen, and lymph nodes of PARP-1 knockout (KO) mice compared with wild-type (WT) controls. The increased frequency of regulatory T cells in the periphery resulted in impaired CD4 cell proliferation and IL-2 production, which could be restored by CD25(+) cell depletion. Phenotype and inhibitory functions of PARP-1 KO regulatory T cells were similar to WT cells, indicating that PARP-1 affects regulatory T cell differentiation rather than function. Purified naive CD4 cells from PARP-1 KO mice stimulated in vitro expressed forkhead box p3 mRNA at higher levels and generated a greater number of Foxp3(+) cells (inducible regulatory T [iTreg] cells) than the WT counterpart. This finding was due to a higher rate of naive CD4 cell to Foxp3(+) iTreg cell conversion rather than to higher resistance to apoptosis induction. Interestingly, PARP-1 deficiency did not affect retinoid-related orphan receptor-gamma t mRNA expression and differentiation of purified naive CD4 cells to Th17 cells. PARP-1 KO iTreg cells showed features similar to WT regulatory T cells, suggesting that modulation of PARP-1 during the immune response might be used to induce greater numbers of functional regulatory T cells. In conclusion, our findings represent the first evidence that PARP-1 can affect regulatory T cell differentiation and open new perspectives on potential targets for modulating immune responses. The Journal of Immunology, 2010, 184: 3470-3477
Opposite roles of poly-(ADP-ribose)-polymerase-1 in Th2 and regulatory T cell differentiation
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