The effect of α-Al2O3 nanoparticles (up to 5 wt.%) on the physical, mechanical, and thermal properties, as well as on the microstructural evolution of a dense magnesia refractory is studied. ...Sintering temperatures at 1300, 1500, and 1600 °C are used. The physical properties of interest were bulk density and apparent porosity, which were evaluated by the Archimedes method. Thermal properties were examined by differential scanning calorimetry. The mechanical behavior was studied by cold crushing strength and microhardness tests. Finally, the microstructure and mineralogical qualitative characteristics were studied by scanning electron microscopy and X-ray diffraction, respectively. Increasing the sintering temperature resulted in improved density and reduced apparent porosity. However, as the α-Al2O3 nanoparticle content increased, the density and microhardness decreased. Microstructural observations showed that the presence of α-Al2O3 nanoparticles in the magnesia matrix induced the magnesium-aluminate spinel formation (MgAl2O4), which improved the mechanical resistance most significantly at 1500 °C.
The optical design of a compact off-axis four-mirror objective system (OFOS) of a thermal camera for a syndromic surveillance system that captures bioclinical signals, like temperature, directly ...related to the physical symptoms of the COVID-19 disease through thermal images is presented. The OFOS design works on wavelengths of 7.5-14 µm, with an
-number of 4, and a field of view (FOV) of 24×4 deg.
Organic luminescent materials have attracted significant attention in the past few years due to their fascinating photophysical properties. Implementing these emissive organic compounds is now being ...actively pursued in many applications in solution (i.e., sensors, bioimaging) or their solid forms (i.e., optoelectronic devices or data encryption). Despite significant advances in the development of emissive compounds, there has been an increasing quest in the past decade for materials where the emission is preserved in both states, dual-state emission (DSE). These compounds are expected to detonate a myriad of applications in the future. On this nascent topic, this work addresses several factors that increase the probability of obtaining the dual-state emission property based on the precedent reports showing this phenomenon. Therefore, this review identifies and organizes the different structural characteristics useful to obtain these compounds. In addition, it has been devised to motivate the discussion in the materials science community and hopefully incentivize the efforts of many research groups around the world toward the synthesis of new dual-state emitters.
Biosorption of Water Pollutants by Fungal Pellets Legorreta-Castañeda, Adriana; Lucho-Constantino, Carlos; Beltrán-Hernández, Rosa ...
Water (Basel),
04/2020, Letnik:
12, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Fungal biosorption is an environmental biotechnology based on the ability of the fungal cell wall to concentrate harmful water pollutants. Among its advantages are its simplicity, high efficiency, ...flexibility of operation, and low cost. The biosorptive performance of fungal pellets is getting growing attention since they offer process advantages over the culture of disperse mycelia, such as an enhanced biomass separation, and a high resilience in severe environmental conditions. In this review, biosorption capacity of fungal pellets towards heavy metals, dyes, phenolic compounds, humic substances, pesticides, and pharmaceuticals was reviewed. Available data about the adsorption capacity of pellets, their removal efficiency, and the operational conditions used were collected and synthesized. The studies relying on biodegradation were discarded to present only the possibilities of fungal pellets for removing these concern pollutants through biosorption. It was found that the biosorption of complex mixtures of pollutants on fungal pellets is scarcely studied, as well as the interfering effect of anions commonly found in water and wastewater. Furthermore, there is a lack of research with real wastewater and at pilot and large scale. These topics need to be further explored to take full advantage of fungal pellets on improving the quality of aquatic systems.
Understanding the impacts of global change on ecological communities is a major challenge in modern ecology. The gain or loss of particular species and the disruption of key interactions are both ...consequences and drivers of global change that can lead to the disassembly of ecological networks. We examined whether the disruption of a hummingbird–mistletoe–marsupial mutualism by the invasion of non‐native species can have cascading effects on both pollination and seed dispersal networks in the temperate forest of Patagonia, Argentina. We focused on network motifs, subnetworks composed of a small number of species exhibiting particular patterns of interaction, to examine the structure and diversity of mutualistic networks. We found that the hummingbird–mistletoe–marsupial mutualism plays a critical role in the community by increasing the complexity of pollination and seed dispersal networks through supporting a high diversity of interactions. Moreover, we found that the disruption of this tripartite mutualism by non‐native ungulates resulted in diverse indirect effects that led to less complex pollination and seed dispersal networks. Our results demonstrate that the gains and losses of particular species and the alteration of key interactions can lead to cascading effects in the community through the disassembly of mutualistic networks.
Concrete is the most used construction material, needing large quantities of Portland cement. Unfortunately, Ordinary Portland Cement production is one of the main generators of CO
, which pollutes ...the atmosphere. Today, geopolymers are an emerging building material generated by the chemical activity of inorganic molecules without the Portland Cement addition. The most common alternative cementitious agents used in the cement industry are blast-furnace slag and fly ash. In the present work, the effect of 5 wt.% µ-limestone in mixtures of granulated blast-furnace slag and fly ash activated with sodium hydroxide (NaOH) at different concentrations was studied to evaluate the physical properties in the fresh and hardened states. The effect of µ-limestone was explored through XRD, SEM-EDS, atomic absorption, etc. The addition of µ-limestone increased the compressive strength reported values from 20 to 45 MPa at 28 days. It was found by atomic absorption that the CaCO
of the μ-limestone dissolved in NaOH, precipitating Ca(OH)
as the reaction product. SEM-EDS analysis showed a chemical interaction between C-A-S-H- and N-A-S-H-type gels with Ca(OH)
, forming (N, C)A-S-H- and C-(N)-A-S-H-type gels, improving mechanical performance and microstructural properties. The addition of μ-limestone appeared like a promising and cheap alternative for enhancing the properties of low-molarity alkaline cement since it helped exceed the 20 MPa strength recommended by current regulations for conventional cement.
•Agroforestry practices occupy less than 10% of the potential European area.•Agroforestry promotion should be simplified in the CAP.•Agroforestry can be linked to arable land, permanent grasslands ...and permanent crops as well as forestlands.
Agroforestry is an integrated land use management that combines a woody component with a lower story agricultural production recognized as one of the most important tools to mitigate and adapt to climate change. The objective of this paper is to provide a categorization and extent of agroforestry practices linked to agricultural and forest lands at regional level and evaluate how are they promoted by the previous (2007–2013) and current CAP (2014–2020) with a special focus on climate change mitigation potential. Agroforestry occupies almost 20 million hectares in Europe, being silvopasture and homegardens the most extensively spread practices and forest farming not quantified. Agroforestry practices are promoted at European level but in a really complex form as more than 25 measures are implemented to enhance the existing 5 agroforestry practices (silvopasture, silvoarable, riparian buffer strips, forest farming and homegardens). Simplification of the number of measures to promote agroforestry practices is needed to better follow up the implementation and to evaluate and provide future policies more adapted at European levels. Huge potential climate change mitigation options should be focused on the use of silvopasture on forest lands to reduce forest fires and to increase the presence of the woody component on arable lands (silvoarable) but also on the promotion of forest farming and homegardens as forms to increase the use of short supply chains and to increase the connection of urban, periurban and rural areas within a bioeconomy and circular economy framework.
•CS/PVA/GEN and CS/PVA/GEN/MWCNTs are promising materials in tissue engineering.•CS/PVA/GEN/MWCNTs hydrogels showed a photomechanical response under IR-irradiation.•Volume and surface hydrophilicity ...of hydrogels were significantly modified by MWCNTs.•The topology of hydrogels was modified by the addition of MWCNTs and/or genipin.•Adhesion and proliferation of fibroblast cells were improved by OH and NH2 groups.
Photoresponsive membranes were successfully obtained by combining chitosan (CS), poly(vinyl alcohol) (PVA) crosslinked with genipin (GEN) and filled with multi-walled carbon nanotubes (MWCNTs). It was demonstrated that adding a small quantity (0.01% w/v) of MWCNTs conferred to those nanocomposite hybrid hydrogels an outstanding photomechanical response under infrared irradiation. Moreover, it was observed that MWCNTs enhanced the crystallinity, increased the elastic modulus but did not contribute to the thermal stability of the nanocomposite hybrid hydrogels. The swelling capacity and contact angle values of these materials were modified through the addition of MWCNTs, and the offered free OH and NH2 functional groups in their current chemical structures. These functional groups – on hybrid hydrogels' surfaces – also enhanced the adhesion and proliferation of human dermal fibroblast cells, showing typical morphologies and sizes. Additionally, non-cytotoxic effects were observed for these nanocomposite hybrid hydrogels, suggesting their potential use in tissue engineering and biomedical applications.
Chemical compounds studied in this article: Chitosan (PubChem CID: 71853); Polyvinyl alcohol (PubChem CID: 11199); Genipin (PubChem CID: 442424).
Insoluble amyloid fibrils made from proteins and peptides are difficult to be degraded in both living and artificial systems. The importance of studying their physical stability lies primarily with ...their association with human neurodegenerative diseases, but also owing to their potential role in multiple bio-nanomaterial applications. Here, gold nanorods (AuNRs) were utilized to investigate the plasmonic heating properties and dissociation of amyloid-β fibrils formed by different peptide fragments (Aβ16–22/Aβ25–35/Aβ1–42) related to the Alzheimer’s disease. It is demonstrated that AuNRs were able to break mature amyloid-β fibrils from both the full length (Aβ1–42) and peptide fragments (Aβ16–22/Aβ25–35) within minutes by triggering ultrahigh localized surface plasmon resonance (LSPR) heating. The LSPR energy absorbed by the amyloids to unfold and move to higher levels in the protein folding energy landscape can be measured directly and in situ by luminescence thermometry using lanthanide-based upconverting nanoparticles. We also show that Aβ16–22 fibrils, with the largest persistence length, displayed the highest resistance to breakage, resulting in a transition from rigid fibrils to short flexible fibrils. These findings are consistent with molecular dynamics simulations indicating that Aβ16–22 fibrils possess the highest thermostability due to their highly ordered hydrogen bond networks and antiparallel β-sheet orientation, hence affected by an LSPR-induced remodeling rather than melting. The present results introduce original strategies for disassembling amyloid fibrils noninvasively in liquid environment; they also introduce a methodology to probe the positioning of amyloids on the protein folding and aggregation energy landscape via nanoparticle-enabled plasmonic and upconversion nanothermometry.
Water quality regulations entail a substantial commitment of resources from governments and private entities. It is important to continually evaluate the effectiveness of these regulations to ensure ...they are having the intended impact. In this paper, we evaluated nutrient data as indicators of primary productivity and dissolved oxygen (DO) concentrations and pH as response variables to assess historical water quality trends from 55 stations of Puerto Rico. The stations were divided into impaired versus non‐impaired categories based on their historical total phosphorus (TP) mean concentration. Mean TP and total nitrogen (TN) concentrations were significantly higher in the impaired stations relative to the non‐impaired stations. In contrast, DO mean concentrations and mean pH values were significantly lower in the impaired stations. A generalized additive mixed model was used to demonstrate temporal trends. A significant decrease in TP and TN concentrations was observed with time at the impaired stations. This was accompanied by significant increases in DO concentrations and pH. The non‐impaired stations showed a marginal (statistically nonsignificant) decreasing trend with time. The large reductions in nutrient concentrations observed at the impaired stations seem to be related to the closure of several primary wastewater treatment plants (WWTPs) across the island. The conversion of abandoned crop agricultural lands into secondary forest in recent decades has resulted in small but significant decreases in TN (not TP) in receiving streams. We conclude that the Clean Water Act has promoted improvements in water quality in Puerto Rico by advancing upgrades in sanitary infrastructure and the regulation of point sources of pollution.
Core Ideas
The effectiveness of the Clean Water Act on the water quality of streams of Puerto Rico was assessed.
Historical trends in nutrient concentrations show significant improvement for the most impaired streams.
Residual discharges from wastewater treatment plants (WWTPs) were identified as a major source of impairment.
The closure of outdated WWTP plants generated a positive impact on water quality.
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