Mixed Aggregates Research Articles

Protein ingredient quality of infant formulas impacts their structure and kinetics of proteolysis under in vitro dynamic digestion

Infant formula (IF) is a complex matrix requiring numerous ingredients and processing steps. The objective was to understand how the quality of protein ingredients impacts IF structure and, in turn, their kinetics of digestion. Four powdered IFs (A/B/C/D), based on commercial whey protein (WP) ingredients, with different protein denaturation levels and composition (A/B/C), and on caseins with different supramolecular organisations (C/D), were produced at a semi-industrial level after homogenization and spray-drying. Once reconstituted in water (13 %, wt/wt), the IF microstructure was analysed with asymmetrical flow field-flow fractionation coupled with multi-angle light scattering and differential refractometer, transmission electron microscopy and electrophoresis. The rehydrated IFs were subjected to simulated infant in vitro dynamic digestion (DIDGI®). Digesta were regularly sampled to follow structural changes (confocal microscopy, laser-light scattering) and proteolysis (OPA, SDS-PAGE, LC-MS/MS, cation-exchange chromatography). Before digestion, different microstructures were observed among IFs. IF-A, characterized by more denatured WPs, presented star-shaped mixed aggregates, with protein aggregates bounded to casein micelles, themselves adsorbed at the fat droplet interface. Non-micellar caseins, brought by non-micellar casein powder (IF-D) underwent rearrangement and aggregation at the interface of flocculated fat droplets, leading to a largely different microstructure of IF emulsion, with large aggregates of lipids and proteins. During digestion, IF-A more digested (degree of proteolysis + 16 %) at 180 min of intestinal phase than IF-C/D. The modification of the supramolecular organisation of caseins implied different kinetics of peptide release derived from caseins during the gastric phase (more abundant at G80 for IF-D). Bioactive peptide release kinetics were also different during digestion with IF-C presenting a maximal abundance for a large proportion of them. Overall, the present study highlights the importance of the structure and composition of the protein ingredients (WPs and caseins) selected for IF formulation on the final IF structure and, in turn, on proteolysis. Whether it has some physiological consequences remains to be investigated.

Pink salmon fishery in the Far-Eastern fishing basin in 2022: preliminary studies, forecast, interpretation of the fishing season results

Results of marine trawl surveys for accounting of pink salmon in 2021 and 2022 and the main results of the salmon fishery in 2022 are presented. The main stages of forecasting of the pink salmon fishery in the Far Eastern basin are described. Differentiation of mixed aggregations of pink salmon is discussed. In 2022, specialists of Kamchatka Branch used for the first time a new method based on variability of SNP loci, along with the traditional methods (morphological express-method and genetic method based on mtDNA analysis). This method provided additional dividing the mixed aggregations of autumn pink salmon in the Sakhalin-Kuril area to the herds from southern Kuril Islands and from eastern Sakhalin. The fishery forecasts for pink salmon were adjusted several times during the fishing season. These adjustments had no a significant effect for the catch increasing in the Okhotsk Sea basin, but allowed to land 10,500 t additionally in the Bering Sea.

California sea lions interfere with striped marlin hunting behaviour in multi-species predator aggregations.

The open ocean offers a suite of ecological conditions promoting the occurrence of multi-species predator aggregations. These mixed predator aggregations typically hunt large groups of relatively small and highly cohesive prey. However, the mechanisms and functions of these mixed predator aggregations are largely unknown. Even basic knowledge of whether the predator species' interactions are mutualistic, commensal or parasitic is typically missing. Moreover, recordings of attack and capture rates of marine multi-species predator aggregations, which are critical in understanding how and why these interactions have evolved, are almost completely non-existent owing to logistical challenges. Using underwater video, we quantified the attack and capture rates of two high-trophic level marine predators, California sea lions (Zalophus californianus) and striped marlin (Kajikia audax) attacking schools of fishes in the Southern California Current System, offshore the Baja California Peninsula. Recording over 5000 individual attacks across 13 fish schools, which varied in species, size and predator composition, we found that sea lions kleptoparasitized striped marlin hunts and reduced the frequency of marlin attacks and captures via interference competition. We discuss our results in the context of the phenotypic differences between the predator species and implications for a better understanding of multi-species predator aggregations. This article is part of the theme issue 'Mixed-species groups and aggregations: shaping ecological and behavioural patterns and processes'.

Understanding the process of phosphate removal in Fe0/H2O systems using the methylene blue method

The removal mechanisms of contaminants in Fe0/H2O are still poorly understood, and characterized by contradictory findings. Therefore, the present study aims to improve the understanding of the processes involved in phosphate removal in Fe0/H2O system. Herein, the methylene blue method (MB method) is used to trace the dynamics within the investigated systems. The MB method utilizes the differential adsorptive affinity of MB onto sand and sand coated with iron corrosion products to evaluate the degree of Fe0 corrosion in Fe0/H2O systems. The extent of MB discoloration and phosphate removal in various Fe0-based systems was characterized in parallel quiescent batch experiments for two weeks and two months. Parallel experiments with Orange II (O-II) as a model contaminant allowed an improved discussion of the results. The investigated systems were: (i) Fe0 alone, (ii) MnO2 alone, (iii) sand alone, (iv) Fe0 + sand, (v) Fe0 + MnO2, and (vi) Fe0 + sand + MnO2. Additional experiments were conducted to test the influence of Fe0 type, Fe0 and sand mass loadings on dye discoloration and phosphate removal in Fe0/sand system. Each system was characterized by: (i) pH value, (ii) Fe concentration, (iii) dye discoloration (MB, O-II), and (iv) phosphate concentration. Results showed that the MB method was capable of tracing the extent of iron corrosion in the various investigated systems and clarified the role of in-situ generated iron corrosion products (FeCPs) in the removal of phosphate. The suitability of mixing sand aggregates with Fe0 for efficient phosphate removal is demonstrated through the MB method. Overall, the appropriateness of the MB method to characterize the dynamics of Fe0/H2O systems is validated.

Insights into the single-particle composition, size, mixing state, and aspect ratio of freshly emitted mineral dust from field measurements in the Moroccan Sahara using electron microscopy

Abstract. The chemical and morphological properties of mineral dust aerosols emitted by wind erosion from arid and semi-arid regions influence climate, ocean, and land ecosystems; air quality; and multiple socio-economic sectors. However, there is an incomplete understanding of the emitted dust particle size distribution (PSD) in terms of its constituent minerals that typically result from the fragmentation of soil aggregates during wind erosion. The emitted dust PSD affects the duration of particle transport and thus each mineral's global distribution, along with its specific effect upon climate. This lack of understanding is largely due to the scarcity of relevant in situ measurements in dust sources. To advance our understanding of the physicochemical properties of the emitted dust PSD, we present insights into the elemental composition and morphology of individual dust particles collected during the FRontiers in dust minerAloGical coMposition and its Effects upoN climaTe (FRAGMENT) field campaign in the Moroccan Sahara in September 2019. We analyzed more than 300 000 freshly emitted individual particles by performing offline analysis in the laboratory using scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectrometry (EDX). Eight major particle-type classes were identified with clay minerals making up the majority of the analyzed particles both by number and mass, followed by quartz, whereas carbonates and feldspar contributed to a lesser extent. We provide an exhaustive analysis of the PSD and potential mixing state of different particle types, focusing largely on iron-rich (Fe oxide-hydroxides) and feldspar particles, which are key to the effects of dust upon radiation and clouds, respectively. Nearly pure or externally mixed Fe oxide-hydroxides are present mostly in diameters smaller than 2 µm, with the highest fraction below 1 µm at about 3.75 % abundance by mass. Fe oxide-hydroxides tend to be increasingly internally mixed with other minerals, especially clays, as particle size increases; i.e., the volume fraction of Fe oxide-hydroxides in aggregates decreases with particle size. Pure (externally mixed) feldspar represented 3.2 % of all the particles by mass, of which we estimated about a 10th to be K-feldspar. The externally mixed total feldspar and K-feldspar abundances are relatively invariant with particle size, in contrast to the increasing abundance of feldspar-like (internally mixed) aggregates with particle size with mass fractions ranging from 5 % to 18 %. We also found that overall the median aspect ratio is rather constant across particle size and mineral groups, although we obtain slightly higher aspect ratios for internally mixed particles. The detailed information on the composition of freshly emitted individual dust particles and quantitative analysis of their mixing state presented here can be used to constrain climate models including mineral species in their representation of the dust cycle.

Strength Reduction of Concrete Subjected to High Temperatures: Effects of Various Aggregates

Previous studies on the strength degradation of concrete subjected to high temperatures were analyzed. To analyze the effect of the coarse-aggregate type on strength degradation, data from previous studies were collected, and the coarse aggregate used, physical properties of the aggregate, and heating conditions were analyzed. The concrete types were classified into normal, heavyweight, and lightweight concrete. Their high-temperature characteristics were analyzed and evaluated according to the mixed coarse aggregate. Finally, the correlations derived from the analysis results were compared with the CEB Code. The analysis results were different for different concrete and coarse-aggregate types, and different tendencies from the CEB Code were observed.

Molecular Insights on Morphology, Composition, and Stability of Mixed Micelles Formed by Ionic Surfactant and Nonionic Block Copolymer in Water Using Coarse-Grained Molecular Dynamics Simulations.

The nanoscale association domains are the ultimate determinants of the macroscopic properties of complex fluids involving amphiphilic polymers and surfactants, and hence, it is foremost important to understand the role of polymer/surfactant concentration on these domains. We have used coarse-grained molecular dynamics simulations to investigate the effect of polymer/surfactant concentration on the morphology of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO, i.e., pluronics or poloxamers) block copolymer, and ionic surfactants sodium dodecyl sulfate (SDS), mixed micelles in aqueous solution. The proclivity of the surfactant to form the mixed micelles is also probed using umbrella sampling simulations. In this study, we observed that the core of the pluronic + SDS formed mixed micelles consists of PPO, the alkyl tail of SDS, and some water molecules, whereas the PEO, water, and sulfate headgroups of SDS form a shell, consistent with experimental observations. The micelles are spherical at high-pluronic/low-SDS compositions, ellipsoidal at high-SDS/low-pluronic compositions, and wormlike-cylindrical at high-pluronic/high-SDS compositions. The transitions in micelle morphology are governed by the solvent accessible surface area of mixed aggregates, electrostatic repulsion between SDS-headgroups, and dehydration of PEO and PPO segments. The free energy barrier for SDS escape is much higher in mixed micelles than in pure SDS micelles, indicating a stronger tendency for SDS to form pluronic-SDS mixed micelles.

Multi-Objective Taguchi Optimization of Cement Concrete Incorporating Recycled Mixed Plastic Fine Aggregate Using Modified Fuller’s Equation

Motivated by the multiple benefits of recycling plastic ingredients in cementitious materials, the present study focuses on the design of sustainable cement concrete incorporating recycled mixed plastic fine aggregate (MPFA) as a partial replacement of natural sand (NS). The MPFA produced in this work is composed of a combination of polymer types with similar concoctions to those observed in the postconsumer waste streams. This study approach is vastly different from past reported studies on the use of sorted, highly purified single-type recycled plastic aggregate in cement concrete. A multi-criteria decision-making technique, Best-Worst Method (BWM), was integrated with the Taguchi method to maximize the quality of MPFA concrete based on the Fuller–Thompson theory. More specifically, an L9 (34) Taguchi orthogonal array with four three-level design factors was adopted to optimize the fresh, durability, and mechanical properties of MPFA concrete. The results showed that MPFA concrete produced with 400 kg/m3 cement content, 0.43 water/cement ratio, 0.43 fine aggregate/total aggregate ratio, and 10 vol% MPFA content exhibited the highest quality. Findings from the present work also revealed that MPFA concrete produced with tailored particle size distribution of MPFA NS fine aggregate system achieved superior, if not comparable, qualities to those of conventional concrete.

Synergic effect of recycled aggregate, fly ash, and hydrated lime in concrete production

The use of construction and demolition waste (CDW) as recycled aggregate (RA) and fly ash (FA) in the composition of cementitious materials can make the resulting concrete more sustainable. However, RA is more heterogeneous, porous, and less dense than the natural aggregate (NA), influencing the mechanical strength. On the other hand, the reaction of FA with hydration products of Portland cement is slow, delaying the strength development at an early age. An alternative to increase the strength of concrete with FA at an early age is using the hydrated lime (HL). This research intends to evaluate the efficiency of adding HL in concrete with RA and FA. In this way, this research intends to evaluate the efficiency of adding HL in concretes with RA and FA and comprises two stages. First, a w/c ratio of 0.55 and a replacement of 50% natural coarse aggregate by concrete recycled aggregate (CRA) and mixed concrete aggregate (MRA) was established, considering similar compressive strengths. In the second stage, the properties of concretes with 20% FA in partial replacement of Portland Cement (PC), adding HL at 5% and 10% (by mass) were evaluated. The results showed that concretes with CRA present performance better than concretes with MRA, and the effect of HL was significant for all properties investigated. Concretes with CRA, FA, and 10% HL improved the compressive strength by 12.47%, reduced water absorption and porosity by 9.87% and 23.82%, respectively, and increased apparent density by 8.77% compared to the mixture without HL. The SEM analysis showed the beneficial effect of HL in concretes with RA, due to the high availability of calcium hydroxide. For concretes with RCA, a reduction in the mean equivalent diameter of 62.29% was verified; for concretes with MRA, this reduction was 23.25%. A reduction of carbonation depth was observed when concretes with MRA, FA and 10% HL showed a carbonation coefficient 44.5% lower than concrete without HL after 35 days of exposure to CO2, while concretes with CRA presented a carbonation coefficient of 87.7% lower.

Mixed micelles and gels of a hydrophilic poloxamine (Tetronic 1307) and miltefosine: Structural characterization by small-angle neutron scattering and in vitro evaluation for the treatment of leishmaniasis

Hypothesis/background: Tetronic® is a family of four-armed amphiphilic block copolymers of polyethylene oxide (PEO) and polypropylene oxide (PPO) that self-aggregate to form micelles and hydrogels. Due to their temperature and pH-responsiveness, they are emerging as smart nanomaterials in the area of drug delivery. Here we propose the use of Tetronic 1307 (T1307) as a nanocarrier of miltefosine (MF), a zwitterionic alkylphospholipid highly active against leishmaniasis, one of the most threating neglected tropical diseases. Given the amphiphilic nature of the drug, both surfactants can combine to form mixed micelles, reducing the cytotoxicity of MF by lowering its dose and improving its internalization, hence its antileishmanial effect.Experiments: The structure of the T1307 micelles, MF micelles, mixed micelles and hydrogels, formed in buffered solution (pH = 7.4) at different concentrations has been investigated in-depth by a combination of small-angle neutron scattering (SANS), dynamic light scattering (DLS), fluorescence spectroscopy and nuclear magnetic resonance methods (1D, 2D NOESY, and diffusion NMR). The cytotoxicity of the aggregates in macrophages has been assessed, as well as the antileishmanial activity in both Leishmania major promastigotes and amastigotes.Findings: T1307 and MF combine into mixed aggregates over a wide range of temperatures and compositions, forming ellipsoidal core–shell mixed micelles. The shell is highly hydrated and comprises most of the PEO blocks, while the hydrophobic core contains the PO blocks and the MF along with a fraction of EO and water molecules, depending on the molar ratio in the mixture. The combination with T1307 amplified the leishmanicidal activity of the drug against both forms of the parasite and dramatically reduced drug cytotoxicity. T1307 micelles also showed a considerable leishmanicidal activity without exhibiting macrophage toxicity. These results support the use of T1307 as a MF carrier for the treatment of human and animal leishmaniasis, in its different clinical forms.

SDAFA: Secure Data Aggregation in Fog-Assisted Smart Grid Environment

The tremendous growth of about 8 billion devices connected to each other in various domains of Internet of Things (IoT)-based applications have attracted researchers from both industry and academia. IoT is a network of several devices connected with each other to provide sensing capabilities, particularly in smart grid (SG) environment. Various challenges such as the efficient handling of massive IoT data can be addressed with advances in fog computing. The secure data aggregation challenge is one such issue in IoT-based smart grid systems, which include millions of smart meters. Typical SG-based data aggregation approaches have high computation and communication costs, however, many efforts have been made to overcome these limitations while leveraging fog computing but no satisfactory results have been obtained. Moreover, existing solutions also suffer from high storage requirements. The traditional data aggregation schemes such as GCEDA (Grouping of Clusters for Efficient Data Aggregation) and SPPDA (Secure Privacy-Preserving Data Aggregation) also suffer from a few shortcomings. SPPDA follows a mixed aggregation architecture that includes trees and clusters which can lead to some performance complexities and is not energy-efficient, whereas GCEDA does not support heterogeneity. To overcome these problems, this research provides a fog-assisted strategy for secure and efficient data aggregation in smart grid. The concept of smart grid is implemented in fog environment, which was not the case in previous schemes. We used communication between smart meters (SMs) and fog nodes (FNs) to transmit confidential data in compressed form towards FN. The FN further aggregates the received data which can then be updated in cloud repositories later. We presented two algorithms—data aggregation and data extraction at FN and cloud, respectively, to achieve secure communication. The performance of the proposed strategy has been evaluated against existing data aggregation techniques GCEDA and SPPDA for various performance parameters such as storage, communication cost and transmission cost. The proposed scheme overcomes the limitation of heterogeneity and mixed aggregation which was faced in GCEDA and SPPDA and the results revealed outstanding performance in comparison with both, so the proposed solution can be used in a smart grid environment for efficient and secure data transmission.

Enantioselective [2,3]-Wittig Rearrangement of Carboxylic Acid Derived Enolates by Tetradentate Chiral Lithium Amide

AbstractA chiral lithium amide mediated enantioselective [2,3]-Wittig rearrangement of carboxylic acid enolate has been developed. The reaction proceeds through the formation of a chiral mixed aggregate that shields one enantioface of enolate anion to give a highly functionalized chiral α-hydroxycarboxylic acid.

Development of energy-saving innovative hydraulic mortars reusing spent coffee ground for applications in construction

This paper reports the development of green bio-composite mortars, obtained reusing spent coffee ground (SCG), an agri-food residue, in the light of the Circular Economy approach. This process can boost the sustainability in Construction and proposes an alternative to SCG disposal in landfill, potentially dangerous to humans and the environment. For the first time, specimens were produced and compared using different blends of conventional hydraulic binders (ordinary Portland cement and natural hydraulic lime); SCG partially substituted sand (up to 15 wt%, with a 2.5% increment) for the aggregate mix. The manufacturing process was performed at ambient conditions (20 °C, 65% RH) resulting highly sustainable, and consisted of simple operative steps reproducible in a real building site. The prepared mixes were fully characterised to assess their technological potentials in construction. Morphology analysis, performed by Scanning Electron Microscopy (SEM), showed SCG addition led to a more compact structure. Considering the functional properties, results widely range on binder blend base, offering various concrete applications; it was observed that with SCG addition, despite a decrease in the bulk density (up to 26%), the mechanical performance still remained suitable for proper masonry applications, according to the relevant standards (class of resistance M2.5-M10). A light water imbibition increase was registered (about 5%) while a significant decrease of the capillarity index was seen. Moreover, a robust thermal conductivity reduction was observed (up to 72%), making the mortars highly suitable for energy-saving uses in building. Finally, a reduction in the manufacturing cost (up to 8%) was calculated, granting significant financial saving in light of the industrial symbiosis. These encouraging results showed that reusing SCG not only provides numerous benefits to the overall building performance and management but it is also a valid alternative to usual SCG disposal. The high amount of reused bio-waste significantly widens the knowledge of greener and more efficient building sector, making the prepared mortars promising candidates for the Minimum Environmental Criteria certification, in light of the recent EU regulations, and in line with the principles of the Circular Economy.

ANÁLISIS DE LA VIABILIDAD TÉCNICA Y MEDIOAMBIENTAL DE LOS MORTEROS DE CEMENTO ELABORADOS CON ÁRIDO RECICLADO MIXTO

The construction industry is one of the main economic drivers of nations, but it is also an industry that generate a large amount of waste that cause a strong negative environmental impact. This research studies the effect of partial or total substitution of natural aggregate by mixed recycled aggregate in the manufacture of cement mortars. To this end, an experimental study was carried out to examine the mechanical properties and evaluate the shrinkage of mortars made with different proportions of mixed recycled aggregate, to subsequently improve these properties by adding reinforcement fibres to the mortars. The results show how from 50% replacement of natural aggregate the technical performance of the mortars is affected, and how basalt fibre is postulated as a suitable reinforcement for these construction materials. In addition, the carbon footprint derived from the manufacturing process of the mixed recycled aggregate has been determined, which is lower than that obtained for natural aggregate.

Optimization of fiber-reinforced concrete composite with recycled aggregate and fiber produced with mixed plastic waste

The concept of recycling single-type plastic wastes sorted from post-consumer waste streams in concrete materials as a sustainable alternative to natural sand and virgin reinforcement fiber has been widely explored in the literature. However, plastic wastes present in post-consumer waste streams largely vary in terms of polymer types, grades, shapes, and sizes among other cross contaminated waste materials. Hence, adoption of results from past studies which require single-type plastic wastes of high purity for use in concrete remains challenging in practice. Therefore, this study proposes the development of mixed plastic aggregate (MPA) and mixed plastic fiber (MPF) with similar polymer composition to those of mixed plastic wastes in post-consumer waste streams. The Taguchi method with multi-responses utility concept was applied to formulate an optimal high strength mixed plastic fiber-reinforced concrete composite (MPFRCC) mixture incorporating MPA and MPF. Six quality characteristics, such as slump, surface resistivity, compressive strengths at 1, 7 and 28 days and flexural strength at 28 days were characterized based on four three-level design factors, namely polymeric composition of MPA and MPF, MPA replacement level by volume of natural sand (NS), MPF content by volume of total mixture and water/cement ratio. This work demonstrates a promising and effective approach to assimilate the continual generation and accumulation of mixed plastic waste whilst reducing the reliance on consumption of NS and synthetic virgin fiber by the construction industry using recycled MPA and MPF in MPFRCC for building and infrastructural applications.

Deep learning-based software and hardware framework for a noncontact inspection platform for aggregate grading

Due to the problem of complex aggregate stacking and adhesion, current construction site aggregate grade detection relies on traditional screening methods and single digital image processing technology, which causes inefficiency and segmentation identification difficulties. This problem has become a technical bottleneck in achieving automatic construction site mixed aggregate grade detection. This study constructs a noncontact testing platform for aggregate gradation based on a self-developed sampling and testing device for mixed aggregate gradation and improved deep learning algorithms, which enables rapid testing of mixed aggregate gradation. Based on the principle of instance segmentation, each aggregate in the stacked mixed aggregates collected based on hardware observation is used as an instance to detect independent aggregate targets in the mixed aggregate images with different moisture contents, sand contents and cohesive stacking. An improved aggregate segmentation convolutional neural network model (AS Mask RCNN: Aggregate Segmentation Mask RCNN) is used to achieve the gradation detection of mixed aggregates. This study employed three different types of experiments, and the results showed that the AS Mask RCNN network model achieved an accuracy of over 89.13% in the three experimental situations, and compared the results with those of the Faster RCNN and Mask R-CNN models, with an accuracy improvement of 8.85% and a reduction of 1.29 s in the processing time of a single image segmentation, which can meet the field near real-time detection requirements. The self-developed noncontact testing platform for aggregate grading can adapt to practical applications in complex environments, enabling digital, automated and intelligent noncontact rapid testing of mixed aggregate grading, further improving the accuracy of aggregate grading testing and serving the high-quality development of reservoir dam construction in China.

Assessing Compressive Strength of Concrete with Waste Automobile Tire and Palm Kernel shells as Aggregates

All throughout the world, millions of end-of-service life automobile tires and Palm Kernel Shells (PKS) are generated as waste that require proper disposal. The reuse of these wastes in concrete is regarded as a novel approach that has environmental, health and performance related benefits. On this basis, the current study was designed to investigate the coupled effect of using both PKS and tire chips as aggregates in concrete mixes on the compressive strength and other properties of concrete. A total of twenty-one (21) concrete mixes containing different volumes of PKS and tire chips as a partial to full replacement of the conventional crushed granite aggregates were prepared to evaluate their impact on the fresh (i.e. slump) and hardened (i.e. density and compressive strength) properties of the concrete at 7, 14, 21, 28, 56 and 90days of curing. The results showed that there is a systematic decrease in compressive strength, workability and density of concrete with increase in tire (T) and PKS (P) content. However, up to 50% total aggregate replacement (TAR) level, adequate compressive strength can be achieved for structural purposes. At this optimum point, the mix with P75T25 recorded a compressive strength of 13.27 N/mm2 which represents about 44% of the strength of the control mix. Generally, the inclusion of PKS aggregates improves compressive strength and decrease the rate of strength reduction.

Characterization of Three Types of Recycled Aggregates from Different Construction and Demolition Waste: An Experimental Study for Waste Management

Achieving sustainable management and efficient use of natural resources stands out as one of the goals included in the Goals for Sustainable Development in the 2030 Agenda. The construction sector is currently far from presenting an efficient model in terms of treating waste generated by it. Variations in the physical and chemical properties of recycled aggregates coming from construction and demolition waste are one of the main reasons of their limited use in the production of construction materials. This research presents a physicochemical characterization of three different types of recycled aggregates coming from different types of waste: concrete, ceramic and mixed. Physical characterization shows that recycled concrete aggregate has better physical properties compared with mixed recycled aggregate and ceramic recycled aggregate, which makes it more suitable for use in masonry mortars and concrete, due to its higher dry density (2210.33 kg/m3), its lower content of fines (5.17%), its lower friability coefficient (24.60%), and its water absorption coefficient (6.70%). Chemical characterization shows that none of the tested recycled aggregates contains traces of harmful chemical agents that exceed the limits established by the reference regulations. Finally, the statistical analysis shows good homogeneity for these raw materials, obtaining low coefficients of variation and values within the recommended in each of the calculated confidence intervals.

A Drop-on-Demand Bioprinting Approach to Spatially Arrange Multiple Cell Types and Monitor Their Cell-Cell Interactions towards Vascularization Based on Endothelial Cells and Mesenchymal Stem Cells.

Spheroids, organoids, or cell-laden droplets are often used as building blocks for bioprinting, but so far little is known about the spatio-temporal cellular interactions subsequent to printing. We used a drop-on-demand bioprinting approach to study the biological interactions of such building blocks in dimensions of micrometers. Highly-density droplets (approximately 700 cells in 10 nL) of multiple cell types were patterned in a 3D hydrogel matrix with a precision of up to 70 μm. The patterns were used to investigate interactions of endothelial cells (HUVECs) and adipose-derived mesenchymal stem cells (ASCs), which are related to vascularization. We demonstrated that a gap of 200 μm between HUVEC and ASC aggregates led to decreased sprouting of HUVECs towards ASCs and increased growth from ASCs towards HUVECs. For mixed aggregates containing both cell types, cellular interconnections of ASCs with lengths of up to approximately 800 µm and inhibition of HUVEC sprouting were observed. When ASCs were differentiated into smooth muscle cells (dASCs), separate HUVEC aggregates displayed decreased sprouting towards dASCs, whereas no cellular interconnections nor inhibition of HUVEC sprouting were detected for mixed dASCs/HUVEC aggregates. These findings demonstrate that our approach could be applied to investigate cell-cell interactions of different cell types in 3D co-cultures.

Review of Geotechnical Properties of Reclaimed Asphalt Pavement for Reuse in Infrastructure

Reclaimed Asphalt Pavement (RAP) has been extensively studied for potential use as a recycled material in infrastructure construction. There is consensus that utilization of RAP provides environmental and economic benefits for most projects. However, impacts to engineering performance are less known, owing to the highly variable nature of RAP sources with different asphalt pavement mixtures and milling processes, which has limited the adoption of RAP as fill material in geotechnical infrastructure. This study conducted a comprehensive review of geotechnical properties reported for RAP in the experimental literature. The gradation, specific gravity, density, moisture content, hydraulic conductivity, leaching, shear strength, and creep properties of different RAP sources are summarized and compared. These geotechnical properties, as well as recent investigations into the effects of temperature and aggregate mixing, were used to identify the potential reuse of RAP in highway transportation applications beyond just asphalt mixture design, such as embankments. Additionally, correlations between gradation properties (Cu, D10, D85), asphalt content, and the geotechnical properties of maximum dry density, saturated hydraulic conductivity, and shear strength were identified.