Numerical simulation of tidal-driven particulate dispersion and transport in a Larimichthys crocea enclosure aquaculture zone.

For an extended period of time, the meninges were believed to be devoid of lymphatic vessels. The recent discovery of lymphatic vessels in the dura mater of humans, mice and zebrafish, and the identification and characterization of scavenging lymphatic endothelial cells in zebrafish leptomeninges have contributed to a better understanding of waste removal routes from the brain. Zebrafish brain lymphatic endothelial cells (BLECs), in particular, have a high propensity for particulate waste removal from the cerebrospinal fluid. To further understand the function of BLECs, we have established a protocol for specifically ablating this cell type during embryonic stages. We show that BLECs do not recover upon complete depletion, even at adult stages. The absence of BLECs results in detrimental effects on the meningeal blood vasculature and on arachnoid mater structure. We further report that, upon BLEC ablation, a vessel network forms, which shares characteristics with lymphatic vessels and is able to take up substances injected into the brain parenchyma, thus possibly providing compensatory functions in the absence of BLECs.

It is often assumed planktonic cyanobacteria existed in Precambrian oceans, but that their productivity was constrained. However, available evidence suggests picocyanobacteria only colonized the open ocean near the Neoproterozoic-Phanerozoic boundary, close to the start of a period of sustained atmospheric oxygenation. If earlier open oceans were devoid of planktonic cyanobacteria, we lack consensus explanations for why this was the case. Colleagues and I recently introduced the 'chitin raft hypothesis', which argues that accumulating chitin particulate waste associated with the rise of arthropods provided an essential evolutionary stepping stone in the rise of marine picocyanobacteria. According to this hypothesis, chitin particles derived from arthropod exoskeleton moults offered marine picocyanobacteria refugia from environmental stresses in the water column, allowing them to explore-and begin adapting to-the open ocean for the first time. Here, I review the context and implications of this hypothesis. One implication is that Precambrian biospheric productivity was constrained by the total global volume of benthic habitats. Hence, the rise of sub-aerial continents near the Archaean-Proterozoic boundary would have driven a major increase in biospheric productivity, with the expansion of oxygenic photosynthesis into the open ocean and onto the continents near the Proterozoic-Phanerozoic boundary driving a second major increase.This article is part of the discussion meeting issue 'Chance and purpose in the evolution of biospheres'.

The disposal of polypropylene plastic tubes generated by producing seedlings of forest species promotes negative impacts on the environment and human health. These factors have motivated the search for biodegradable and environmentally friendly materials. Thus, the present study aims to evaluate the efficiency and quality of tubes made from particulate waste from cashew nut shells and beeswax in the development of Mimosa caesalpiniifolia Benth. The sustainable tubes were produced using a natural beeswax matrix with proportions of 10, 20, 30, 40, and 50% cashew nut particles. The chemical characterization of the material was performed. The tubes were made in a handmade cardboard mold and P80 wood sandpaper, 35 mm × 125 mm (diameter × length). The quality of the seedlings was evaluated using the Dickson quality index (DQI). The results showed that the cashew nutshell particles present in their chemical composition have values of 6.83 g kg−1 of nitrogen (N), 0.60 g kg−1 of phosphorus (P), and 1.93 g kg−1 of potassium (K). The quality assessment found that all biodegradable tubes had higher DQI values than polypropylene tubes, emphasizing the treatment with 40% of cashew peel particles, which showed a DQI of 0.14, while the polypropylene tube presented a value of 0.09. Therefore, biodegradable tubes seem a sustainable and efficient alternative for replacing polypropylene tubes in cultivating forest seedlings.

In real-world situations, marine fish farms accommodate multiple fish species and cohorts within the farm, leading to diverse farm layouts influenced by cage dimensions, configurations, and intricate arrangements. These cage management practices are essential to meet production demands, however, farm-level complexities can impact model predictions of waste deposition and benthic impact near fish cages. This is of particular importance when the cages are used for integrated multi-trophic aquaculture (IMTA) with benthic feeders, where this waste not only affects environmental conditions but also provides a potential food source. The Cage Aquaculture Particulate Output and Transport (CAPOT) model incorporated multiple species, cohorts, and cage arrangements to estimate waste distribution from a commercial fish farm in the Mediterranean between October 2018 and July 2019. This spreadsheet model estimated dispersion for individual fish cages using a grid resolution of 5 m x 5 m. The study categorized discrete production periods for each fish cage every month, aligning with intermittent changes in biomass and food inputs due to different cage management practices throughout production. This approach facilitated the use of detailed input data and enhanced model representativeness by considering variations in cage biomass, food types, settling velocities, and configurations. Model outputs, represented in contour plots, indicated higher deposition directly below fish cages that varied monthly throughout fish production cycles. Deposition footprints reflected changes in cage biomass, food inputs, and farm-level practices reflecting this real-world scenario where aquaculture does not follow a production continuum. Moreover, cohort dynamics and cage movements associated with the cage management practices of the fish farm influenced the quantity and fate of wastes distributed around fish cages, revealing variability in deposition footprints. Clearly, these findings have important implications for the design of benthic IMTA systems, with species such as sea cucumber and polychaetes. Variability in waste deposition creates challenges in identifying where the benthic organisms should be placed to allow optimal uptake of waste to meet their food requirements and increase survivability. Evidently, models have an important role to play and this study emphasizes the need for representative input data to describe actual food inputs, cage biomass changes, and management practices for more representative farm-scale modelling and essentially to improve particulate waste management. To effectively mitigate benthic impacts through IMTA, models must quantify and resolve particulate waste distribution and impact around fish farms to maintain a balanced system with net removal of wastes. Resolving farm-level complexities provides vital information about the variability of food availability and quality for extractive organisms that helps improve recycling of organic wastes in integrated systems, demanding a more representative modelling approach.

The feeding activities of fish in marine aquaculture have raised concerns about severe benthic pollution within the cage area. This paper suggests removing particulate waste from the cage area through the implementation of artificial upwelling (AU), a method likely to alleviate the organic burden within the cultivation area. A numerical model was developed to simulate AU-induced particulate matter transport under different operating conditions, with the majority of simulation results validated through flume experiments. The influence of particle characteristics, environmental conditions, and engineering parameters of AU on organic matter transport are discussed. In particular, our study offers a detailed analysis of the minimum initial upwelling velocity required to transport particulate waste to a designated distance. It also recommends situating the bottom of the cage above the maximum height of the waste plume to effectively segregate fish from the waste carried by the upwelling.

Silicone monomers are the basic raw materials for the preparation of silicone materials. The secondary dust generated during the preparation of silicone monomer by the Rochow–Müller method is a fine particulate waste with high silicon content. In this paper, the physical and chemical properties of silicon powder after pretreatment were analyzed, and an experimental study was conducted on the use of silicon dust in the preparation of Si3N4, a nitrogen enhancer for steelmaking, by direct nitriding method in order to achieve the resourceful use of this silicon dust. Furthermore, the thermodynamics and kinetics of the nitriding process at high temperatures were analysed using FactSage 8.1 software and thermogravimetric experiments. The results indicate that after holding at a temperature range of 1300~1500 °C for 3 h, the optimal nitriding effect occurs at 1350 °C, with a weight gain rate of 26.57%. The nitridation of silicon dust is divided into two stages. The first stage is the chemical reaction control step. The apparent activation energy is 2.36 × 105 kJ·mol−1. The second stage is the diffusion control step. The silicon dust growth process is mainly controlled by vapor–liquid–solid (VLS) and vapor–solid (VS) mechanisms.

Commercial salmonid farming is typically performed in open-water net cages where interactions between the environment and production unit might be widespread and not easily predicted or controlled. Integrated multi-trophic aquaculture (IMTA) has been suggested to mitigate some of the environmental impacts. Based on empirical data, the assimilation of particulate waste from a commercial fish farm was modeled by two approaches to salmon/blue mussel IMTA: a system with mussels at the surface next to the fish farm and an alternative setup with mussels submerged under the farm. According to the model, 15% of the feed was defecated and assumed available to the mussels and the submerged mussel farm could assimilate 14.6% of the feces. Sensitivity analysis showed that the current speed, the mussel filtration rate, and the proportion of the material that settles slowly had an impact on this assimilation estimate, which could be significantly higher. However, the model did not include assimilation limitations due to particle size, which may contribute significantly to the submerged farm. The mussel farm at the surface mainly received small slow settling particles, and according to the model, only 0.4% of the fish farm waste was assimilated. The maximum obtainable assimilation was 5.5%. The fraction of slowly settling waste had the most pronounced influence on waste assimilation in the mussel farm at the surface. This is also among the most uncertain parameters, since the relative portion of different settling velocities of fish feces is highly variable, and more information on the size distribution of waste is needed.

Solid waste collagen-associated fabrication of magnetic hematite nanoparticle@collagen nanobiocomposite for emission-adsorption of dyes

Research conducted on ceramic materials has been investigating the incorporation of solid waste into their formulations, driven by the proper disposal of such waste and the reduction of negative environmental impacts.This study analyzed the effects of adding aluminum powder residue to the physical properties of ceramic masses with the aim of obtaining new formulations for ceramic tiles.The aluminum residue and the standard mass for ceramic tile production were chemically characterized and homogenized to obtain new formulations with the incorporation of 4%, 6%, 8%, and 10% aluminum powder in the ceramic mass.The specimens were uniaxially pressed and sintered at a temperature of 1,200 C for 2 h, undergoing three different temperatures (100 C, 400 C, and 650 C) for 30 min each.They were evaluated for WA (water absorption), RLq (linear shrinkage), SEM (scanning electron microscopy), and TRF (flexural strength) modulus.The results demonstrate that the addition of aluminum powder residue is feasible in the proposed formulations (4%, 6%, 8%, and 10%), as they enhance the mechanical properties of the ceramics compared to the formulation with 0% residue, at a sintering temperature of 1,200 C.

The recirculating aquaculture systems (RAS) has been proposed to reduce the water consumption of commercial aquaculture. RAS removes organic and particulate waste from fish tank water while also aerating; as such the treated water can be recycled back into the tanks. In this work, we treat the RAS as a batch process such that economic model predictive control (EMPC) can be applied using a mechanistic process model. The EMPC, which considers fish production profits as well as material utility and electricity costs for RAS, is deployed for various water temperatures such that its effect on the fish growth and economics are quantified. Moreover, batch length is also determined through tracking of the process profit trajectory. The results show that the EMPC-operated RAS can substantially increase the fish sales price with time-varying control decisions. Moreover, the EMPC is shown to adjust its operating policy mid-batch to accommodate for temperature disturbances.

The Cage Aquaculture Particulate Output and Transport (CAPOT) model is an easy to use and flexible farm-scale model that can rapidly estimate particulate waste deposition from fish cage production. This paper describes and tests the model and demonstrates its use for Atlantic salmon (Salmo salar) and Atlantic cod (Gadus morhua). The spreadsheet-based model gives outputs for waste distribution in a variety of spatial modelling software formats, used for further analysis. The model was tested at a commercial Atlantic cod farm and commercial Atlantic salmon farm under full production conditions. Sediment trap data showed predictions, using actual recorded feed and biomass data, to be 96% (±36%) similar for Atlantic cod beyond 5 m from the cage edge, giving a satisfactory estimate of local benthic impact in the vicinity of the farm. For Atlantic salmon, using estimated production biomass and FCR (Feed Conversion Ratio) to calculate feed input, the model overestimated wastes directly beneath the cages (120% ± 148%) and underestimated beyond 5 m from the cage edge, being 48% (±42%) similar to sediment trap data. CAPOT is a suitable initial, rapid assessment model to give an overview of potential impact of particulate waste from new or expanded fish cage farms, with little operator expertise by a wide range of stakeholders.

Hydrodynamic analysis of a bottom-placed fine-mesh cage and its effects on the transport of particulate organic waste

SummarySponges, among the oldest extant multicellular organisms on Earth,1 play a key role in the cycling of nutrients in many aquatic ecosystems.2, 3, 4, 5 They need to employ strategies to prevent clogging of their internal filter system by solid wastes,6, 7, 8 but self-cleaning mechanisms are largely unknown. It is commonly assumed that sponges remove solid waste with the outflowing water through distinct outflow openings (oscula).3,9 Here, we present time-lapse video footage and analyses of sponge waste revealing a completely different mechanism of particle removal in the Caribbean tube sponge Aplysina archeri. This sponge actively moves particle-trapping mucus against the direction of its internal water flow and ejects it into the surrounding water from its seawater inlet pores (ostia) through periodic surface contractions that have been described earlier as “sneezing.”10,11 Visually, it appears as if the sponge is continuously streaming mucus-embedded particles and sneezes to shed this particulate waste, resulting in a notable flux of detritus that is actively consumed by sponge-associated fauna. The new data are used to estimate production of detritus for this abundant sponge on Caribbean coral reefs. Last, we discuss why waste removal from the sponge inhalant pores may be a common feature among sponges and compare the process in sponges to equivalent mechanisms of mucus transport in other animals, including humans.

Nanoplastic pollution is increasing worldwide and poses a threat to humans, animals, and ecological systems. High-throughput, reliable methods for the isolation and separation of NMPs from drinking water, wastewater, or environmental bodies of water are of interest. We investigated iron oxide nanoparticles (IONPs) with hydrophobic coatings to magnetize plastic particulate waste for removal. We produced and tested IONPs synthesized using air-free conditions and in atmospheric air, coated with several polydimethylsiloxane (PDMS)-based hydrophobic coatings. Particles were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), superconducting quantum interference device (SQUID) magnetometry, dynamic light scattering (DLS), X-ray diffraction (XRD) and zeta potential. The IONPs synthesized in air contained a higher percentage of the magnetic spinel phase and stronger magnetization. Binding and recovery of NMPs from both salt and freshwater samples was demonstrated. Specifically, we were able to remove 100% of particles in a range of sizes, from 2–5 mm, and nearly 90% of nanoplastic particles with a size range from 100 nm to 1000 nm using a simple 2-inch permanent NdFeB magnet. Magnetization of NMPs using IONPs is a viable method for separation from water samples for quantification, characterization, and purification and remediation of water.

Models of particulate waste production and deposition can be used in performance-based management approaches as cost-effective tools to assess environmental effects of open-pen finfish aquaculture. XLDEPMOD is an MS Excel® spreadsheet-based depositional model for predicting particulate organic carbon (POC) waste production and sedimentation from net-pen cultured finfish. Calculations are based on temperature-dependent fish growth and mass-balance calculations of feed input, growth, respiration and 3 size classes of feces. Depth-average and near-bottom directional currents are used to determine waste dispersion by fitted Gaussian distribution functions. Near-bottom velocity and substrate-based resuspension thresholds and loss of deposited waste due to decomposition and consumption by wild fish and invertebrates are used to calculate net POC sedimentation. The model was applied to 2 Atlantic salmon farms in southwestern Bay of Fundy, Canada. Sensitivity analysis showed that reduction in waste flux due to resuspension depends on the magnitude of current and wave-driven bottom shear and mass fractions of feces with different settling velocities. Depending on depth, current speed, substrate type and fecal mass fractions, resuspension can remove up to 80% of deposited waste from under net-pens. Steep gradients with high rates (>5 g POC m-2 d-1) of sedimentation predicted under and close to cages and lower rates (<1 g POC m-2 d-1) >50 m away are consistent with published DEPOMOD results and sediment trap observations at the farm sites. The model can be used by regulators to determine if acceptable environmental standards for benthic impacts due to waste deposition from salmon aquaculture are being maintained.

Evaluation of the properties of Al-6061 alloy reinforced with particulate waste glass

Particulate waste of bagasse, cocoa pod husk and guinea fowl feathers may be adopted to fabricate epoxy composites due to their properties of biodegradability, lightweight and cheapness. However, most research has excluded the combination of these reinforcements while the optimisation behaviour of the reinforced composites at room temperature water absorption process is not known. To fill this knowledge gap, this paper aims to analyse issues related to optimisation of the mentioned reinforced composites considering Taguchi’s L25 orthogonal array, the smaller the better signal-to-noise criterion and remodelling of signal-to-noise ratio after the exponential smoothening structure for optimisation. The experiment considered 25% reinforcement blends to 75% epoxy resin. But the 25% reinforcement had five formulations among the component reinforcements. The experiment, using tap water, was conducted for 216 days with measurement intervals random. The response table yielded A5B5C4, indicating 158 experimental days, 12.29g of weight gained by the drained composites, and 7.32g of weight gained by composites damped in 190ml of water. The revised response table that has been influenced by the exponential smoothening method yielded A5B5C5, interpreted as 158 days of experiments, 12.29g of weight gained by the drained composites, and 7.44g of weight gained by composites dumped in 190ml of water. Using the damping factors from 0.05 to 1, different combinations as optimal parameters were obtained, assuring the investigator that the method is feasible. Thus, the optimisation assessment could provide a new method of combining the reinforcement to enhance the composite development process using waste.

Almost 150 papers about brain lymphatics have been published in the last 150 years. Recently, the information in these papers has been synthesized into a picture of central nervous system (CNS) "glymphatics," but the fine structure of lymphatic elements in the human brain based on imaging specific markers of lymphatic endothelium has not been described. We used LYVE1 and PDPN antibodies to visualize lymphatic marker-positive cells (LMPCs) in postmortem human brain samples, meninges, cavernous sinus (cavum trigeminale), and cranial nerves and bolstered our findings with a VEGFR3 antibody. LMPCs were present in the perivascular space, the walls of small and large arteries and veins, the media of large vessels along smooth muscle cell membranes, and the vascular adventitia. Lymphatic marker staining was detected in the pia mater, in the arachnoid, in venous sinuses, and among the layers of the dura mater. There were many LMPCs in the perineurium and endoneurium of cranial nerves. Soluble waste may move from the brain parenchyma via perivascular and paravascular routes to the closest subarachnoid space and then travel along the dura mater and/or cranial nerves. Particulate waste products travel along the laminae of the dura mater toward the jugular fossa, lamina cribrosa, and perineurium of the cranial nerves to enter the cervical lymphatics. CD3-positive T cells appear to be in close proximity to LMPCs in perivascular/perineural spaces throughout the brain. Both immunostaining and qPCR confirmed the presence of adhesion molecules in the CNS known to be involved in T cell migration.

Norwegian Atlantic salmon aquaculture is continuing to expand in northern regions dominated by hard- and mixed-bottom substrates. Such habitats contain rich benthic epifaunal communities, including sponges and other sessile invertebrates susceptible to the impacts of particulate material released from finfish farms. Here, conventional soft-sediment sampling techniques are unable to discern the impacts of farm waste, and new monitoring methods and indicator taxa must be identified. This study improves understanding of the impacts of particulate waste released from salmon farms on the density and structure of benthic epifaunal communities on mixed- and hard-bottom substrates. The diversity, density, and composition of epifaunal communities and visually conspicuous benthic infauna were recorded in towed camera transects along the enrichment gradient (~50-800 m) of 3 salmon farms in northern Norway. Elevated fluxes of particulate material in the vicinity of all farms significantly affected epifaunal community composition, as did the coverage of some key substrate types. The defecated mounds of lugworms and the seastar Asterias rubens were notably more abundant near the farms where fluxes were elevated. The sponges Polymastia spp. and Phakellia spp. and the soft coral Duva florida showed significant declines in density with increasing sedimentation and were principal taxa in communities at natural sedimentation levels. Results identify taxa with both positive and negative spatial associations to particulate waste released from finfish farms and the potential for the development of an epifauna indicator-based index for monitoring the environmental impacts of aquaculture in hard- and mixed-bottom dominated substrates.