Cotransport of nanoplastics with nZnO in saturated porous media: From brackish water to seawater.

The ocean serves as a repository for various types of artificial nanoparticles. Nanoplastics (NPs) and nano zinc oxide (nZnO), which are frequently employed in personal care products and food packaging materials, are likely simultaneously released and eventually into the ocean with surface runoff. Therefore, their mutual influence and shared destiny in marine environment cannot be ignored. This study examined how nanomaterials interacted and transported through sea sand in various salinity conditions. Results showed that NPs remained dispersed in brine, while nZnO formed homoaggregates. In seawater of 35 practical salinity units (PSU), nZnO formed heteroaggregates with NPs, inhibiting NPs mobility and decreasing the recovered mass percentage (Meff) from 24.52% to 12.65%. In 3.5 PSU brackish water, nZnO did not significantly aggregate with NPs, and thus barely affected their mobility. However, NPs greatly enhanced nZnO transport with Meff increasing from 14.20% to 25.08%, attributed to the carrier effect of higher mobility NPs. Cotransport from brackish water to seawater was simulated in salinity change experiments and revealed a critical salinity threshold of 10.4 PSU, below which the mobility of NPs was not affected by coexisting nZnO and above which nZnO strongly inhibited NP transport. This study highlights the importance of considering the mutual influence and shared destiny of artificial nanoparticles in the marine environment and how their interaction and cotransport are dependent on changes in seawater salinity.

Biofilm-mediated interactions between plastics and radiocesium in coastal environments.

A ubiquitous distribution of plastic debris has been reported in aquatic and terrestrial environments; however, the interactions between plastics and radionuclides and the radioactivity of environmental plastics remain largely unknown. Here, we characterize biofilms developing on the surface of plastic debris to explore the role of plastic-associated biofilms as an interaction medium between plastics and radiocesium (137Cs) in the environment. Biofilm samples were extracted from plastics (1-50 mm in size) collected from two contrasting coastal areas in Japan. The radioactivity of plastics was estimated based on the 137Cs activity concentration of the biofilms and compared seasonally with surrounding environmental samples (i.e., sediment and sand). 137Cs traces were detected in biofilms with activity concentrations of 21-1300 Bq·kg-1 biofilm (dry weight), corresponding to 0.04-4.5 Bq·kg-1 plastic (dry weight). Our results reveal the interaction between 137Cs and plastics and provide evidence that organic and mineral components in biofilms are essential in 137Cs retention in environmental plastics. Given the ubiquitous distribution of plastic debris in the environment, more attention should be directed to bioaccumulation and the radioecological impacts of plastic-associated radionuclides on ecosystems.

Simulation of rapid sand filters to understand and design sequential iron and manganese removal using reactive transport modelling.

Iron (Fe2+), manganese (Mn2+), and ammonium (NH4+) oxidation processes were studied in three single media and three dual media full-scale rapid sand filters (RSFs) using reactive transport modelling (RTM) in PHREEQC and parameter estimation using PEST. Here, we present the insights gained into the spatial distribution of Fe and Mn mineral coatings in RSFs and its influence on the oxidation sequence and rates. Fe2+ and Mn2+ oxidation predominantly occurred simultaneously in the RSFs, contrary to the expected sequential oxidation based on Gibbs free energy calculations. During backwashing, RSF grains become fully mixed, which initiates heterogeneous Mn2+ oxidation on Mn-coated grains that end up in the top layer. The resulting grains have a mixed Fe/Mn mineral coating, which is limiting heterogeneous Mn2+ oxidation due to the limited Mn mineral surface available. Mixed coatings did not seem to affect Fe2+ oxidation rates, instead oxidation rates were increasing at lower pH. We found that RSFs can be designed to spatially separate Fe2+ and Mn2+ oxidation, which results in optimal conditions for Mn2+ oxidation. The RSF needs to consist of two layers with varying density to inhibit mixing and complete Fe2+ oxidation should occur in the top layer. The developed RTM can be used to estimate the depth at which Fe2+ oxidation is complete, and thus the ideal intersection depth of the two layers. A novel perspective is provided on how mineral coating distribution in single and dual media filters influence removal rates and the sequence of oxidation, which contributes to the design of more efficient groundwater filters.

Diversity of biting midges, mosquitoes and sand flies at four dog shelters in rural and peri-urban areas of Central Morocco.

Blood-feeding arthropods are involved in the transmission of several pathogens that have a major impact on public health. Entomological investigations highlighted the composition, abundance, and diversity of flying hematophagous arthropods at four dog shelters located in central Morocco during an eight-month study, with the aim of discussing their vectorial roles and assessing the risk of these shelters as foci for zoonotic diseases. Monitoring of the arthropod fauna for 64 catch nights resulted in the collection of 2,321 biting midges (Ceratopogonidae), 570 mosquitoes (Culicidae), and 475 sand flies (Psychodidae). Fourteen Culicoides species were recorded and dominant species were Culicoides imicola (55.96%), C. paolae (16.07%), C. circumscriptus (10.29%), and C. newsteadi (5.77%). Three mosquito species were collected, including Culex pipiens s.l. (96.84%), Culiseta longiareolata (2.80%), and Cx. perexiguus (0.36%). Ten sand fly species were collected, including seven Phlebotomus species (62.70%) and three Sergentomyia species (37.30%); Sergentomyia minuta was the most dominant species (34.31%), followed by Phlebotomus sergenti (32.42%), typical Ph. perniciosus (8.63%), Ph. alexandri (6.94%), and Ph. riouxi (6.52%). The coexistence of several vectors in these study areas indicates the potential circulation of a wide range of pathogens, including zoonotic ones, thus requiring the implementation of surveillance and control programs to prevent the emergence and spread of disease outbreaks.

Title: Diversité des culicoïdes, moustiques et phlébotomes collectés au niveau de quatre chenils du Maroc central. Abstract: Les arthropodes hématophages sont impliqués dans la transmission de plusieurs agents pathogènes ayant un impact majeur sur la santé publique. Des investigations entomologiques ont mis en évidence la composition, l'abondance et la diversité des arthropodes hématophages volants dans quatre chenils situés au centre du Maroc au cours d'une étude de huit mois, dans le but de discuter de leurs rôles vectoriels et d'évaluer le risque de ces chenils comme foyers de maladies zoonotiques. Le suivi de la faune des arthropodes au cours de 64 nuits de capture a permis la collecte de 2 321 culicoïdes (Ceratopogonidae), 570 moustiques (Culicidae) et 475 phlébotomes (Psychodidae). Quatorze espèces de Culicoides ont été recensées et les espèces dominantes étaient Culicoides imicola (55,96 %), C. paolae (16,07 %), C. circumscriptus (10,29 %) et C. newsteadi (5,77 %). Trois espèces de moustiques ont été collectées, dont Culex pipiens s.l. (96,84 %), Culiseta longiareolata (2,80 %) et Cx. perexiguus (0,36 %). Dix espèces de phlébotomes ont été collectées, dont sept espèces de Phlebotomus (62,70 %) et trois espèces de Sergentomyia (37,30 %); Sergentomyia minuta était l'espèce dominante (34,31 %), suivie de Phlebotomus sergenti (32,42 %), Ph. perniciosus typique (8,63 %), Ph. alexandri (6,94 %) et Ph. riouxi (6,52 %). La coexistence de plusieurs vecteurs dans ces zones d'étude indique la circulation potentielle d'un large éventail d'agents pathogènes, y compris zoonotiques, ce qui nécessite la mise en œuvre de programmes de surveillance et de contrôle pour prévenir l'émergence et la propagation d'épidémies.

The roles of geometry and viscosity in the mobilization of coarse sediment by finer sediment.

In rivers, the addition of finer sediment to a coarser riverbed is known to increase the mobility of the coarser fraction. Two mechanisms have been suggested for this: a geometric mechanism whereby smaller sizes smooth the bed, increasing near-bed velocity and thus mobility of the larger sizes, and a viscous mechanism whereby a transitionally smooth turbulent boundary layer forms, rendering the coarser grains more mobile. Here, we report on experiments using two sediment mixtures to better understand these proposed mechanisms. In Mixture 1, we used 0.5 and 5 mm grains, and in Mixture 2, we used 2 and 20 mm grains. If the entrainment of coarse gravel by finer sediment is a purely geometric effect, then the addition of finer material should produce the same effect on the mobility of the coarser material for both mixtures because they have the same size ratio. We show that addition of finer material has a different effect on the two mixtures. We observed an increase in the mobility of the coarse fraction for both mixtures, but the increase in coarse fraction mobility for Mixture 1 was almost twice that for Mixture 2. Our experiments show that in addition to the geometric effect, enhancement of coarse gravel transport by finer sediment is also driven by a viscous effect.

Are toe fringes important for lizard burying in highly mobile sand?

Toe fringes are a key innovation for sand dwelling lizards, and the relationship between toe fringe function and substrate properties is helpful in understanding the adaptation of lizards to sand dune environments. We tested the sand burial performance of Phrynocephalus mystaceus on different sand substrates with toe fringe manipulation, with the aim of assessing whether the function of the toe fringes shifts under different substrate properties, especially in highly mobile substrates. The sand burial performance of P. mystaceus was influenced by substrate properties in relation to the toe fringe states of the lizard. After removal of the bilateral toe fringes, the sand burial ability score of P. mystaceus was significantly higher on sand substrates below 100 mesh than on native sand substrates. As the angle of stability of the substrate properties decreased, the sand burial performance of the lizard was even better after the bilateral toe fringes were removed. The results of the LASSO model and the path analysis model showed that the stability angle provided the opposite effect on sand burial performance in different toe fringe states. These results further suggest that the sand burial function of toe fringes may not be suitable for highly mobile sand substrates. It remains to be tested further whether the function of toe fringes is more important for running on sand.

Mechanical properties of aeolian sand cemented via microbially induced calcite precipitation (MICP).

The cementation of desert aeolian sand is a key method to control land desertification and dust storms, so an economical, green and durable process to reach the binding between sand grains needs to be searched. The method based on the microbially induced calcite precipitation (MICP) appeared in recent years as a promising process that proved its efficiency. The feasibility of the MICP technique to treat aeolian sand composed by low clay content, fine particles, low water content and characterized by weak permeability was demonstrated in the present paper. The effects of initial dry density, cementation number and curing time on the permeability and strength of MICP-treated aeolian sand were investigated using permeability tests and unconfined compressive strength (UCS) tests. The microstructure of aeolian sand was observed by scanning electron microscopy (SEM) tests and X-ray diffraction (XRD), aiming to reveal the solidification principle of MICP. The tests result indicated that when the initial dry density and the cementation number rose, the hydraulic conductivity of aeolian sand decreased while the mechanical strength given by UCS values improved. When the initial dry density was 1.65 g/cm3, the curing time was 3 h and the cementation number reached 20, the hydraulic conductivity and UCS reached 0.00151 cm/s and 1050.30 kPa, respectively. With increasing curing time, the hydraulic conductivity first decreased, followed by an increase, while the UCS exhibited an up and then a downtrend. Furthermore, the correlation between UCS values and the CaCO3 content reached a high R2 value equal to 0.912, which confirmed that the cementation occurred in sandy material and governed the soil strengthening. Indeed, the calcium carbonate crystals observed by SEM and XRD enhanced the friction between particles when they wrapped around the sand grains surface, while carbonates reduced the soil permeability when filling the pores and sticking the sand particles together. Finally, the theoretical and scientific knowledge brought by the present study should help in managing sand in desert areas.

Bartonella spp. in Phlebotominae Sand Flies, Brazil.

Bartonella spp. are opportunistic, vectorborne bacteria that can cause disease in both animals and humans. We investigated the molecular occurrence of Bartonella spp. in 634 phlebotomine sand fly specimens, belonging to 44 different sand fly species, sampled during 2017-2021 in north and northeastern Brazil. We detected Bartonella sp. DNA in 8.7% (55/634) of the specimens by using a quantitative real-time PCR targeting the 16S-23S internal transcribed spacer intergenic region. Phylogenetic analysis positioned the Lutzomyia longipalpis sand fly-associated Bartonella gltA gene sequence in the same subclade as Bartonella ancashensis sequences and revealed a Bartonella sp. sequence in a Dampfomyia beltrani sand fly from Mexico. We amplified a bat-associated Bartonella nuoG sequence from a specimen of Nyssomyia antunesi sand fly. Our findings document the presence of Bartonella DNA in sand flies from Brazil, suggesting possible involvement of these insects in the epidemiologic cycle of Bartonella species.

Gels and cells: the Leishmania biofilm as a space and place for parasite transmission.

Leishmania make an abundant glycoprotein and proteophosphoglycan-rich gel, called the promastigote secretory gel, in the anterior midgut of their sand fly vector. This gel is a multi-faceted virulence factor which promotes the survival and transmission of the parasites between hosts. Here, we present the case that Leishmania parasites embedded in the promastigote secretory gel should be redefined as a biofilm as it shares striking similarities in biogenesis, form, and function with biofilms of other unicellular organisms. We believe that this reinterpretation will stimulate new hypotheses and avenues of research to improve our understanding of the developmental programme of Leishmania and the interaction these parasites and other kinetoplastids have with their insect hosts.

The influence of withdrawal-recharging pattern on the deformation characteristics of sand in confined aquifer.

Land subsidence caused by excessive groundwater withdrawal has become a global hazard, which demands further researches and the potential measures to control. Using the FlowTrac Ⅱ consolidation test system, six compression tests were designed to investigate the stress state and stress paths of sand within confined aquifers under conditions of withdrawal and recharging. The deformation characteristics of aquifer sand were studied under different withdrawal-recharging patterns. During pumping and recharge processes, sand deformation responses were observed to lag behind changes in applied stress. The characteristics of this hysteresis effect on deformation were summarized. The alternating phenomenon of rebound and compression of sand deformation under the recharging process is analyzed. When the recharging effect was relatively small than withdrawing effect under the stable withdrawal-recharging pattern, the compression deformation was observed in the recharging process. The research results provide a rational explanation for the continuous compression deformation of the aquifer during groundwater level recovery and offer experimental evidence for the rational design of artificial groundwater recharge in engineering construction.

Microbial community analysis of sand filters used to treat mine water from a closed uranium mine.

Rapid sand filters (RSFs) are employed in a drinking water treatment to remove undesirable elements such as suspended solids and dissolved metal ions. At a closed uranium (U) mine site, two sets of tandemly linked paired RSF systems (RSF1-RSF2 and RSF1-RSF3) were utilized to remove iron and manganese from mine water. In this study, a 16S rRNA-based amplicon sequencing survey was conducted to investigate the core microbes within the RSF system treating the mine water. In RSF1, two operational taxonomic units (OTUs) related to methanotrophic bacteria, Methylobacter tundripaludum (relative abundance: 18.1%) and Methylovulum psychrotolerans (11.5%), were the most and second most dominant species, respectively, alongside iron-oxidizing bacteria. The presence of these OUTs in RSF1 can be attributed to the microbial community in the inlet mine water, as the three most abundant OTUs in the mine water also dominated RSF1. Conversely, in both RSF2 and RSF3, Nevskia sp., previously isolated from the Ytterby mine manganese oxide producing ecosystem, became dominant, although known manganese-oxidizing bacterial OTUs were not detected. In contrast, a unique OTU related to Rhodanobacter sp. was the third most abundant (8.0%) in RSF1, possibly due to selective pressure from the radionuclide-contaminated environment during RSF operation, as this genus is known to be abundant at nuclear legacy waste sites. Understanding the key bacterial taxa in RSF system for mine water treatment could enhance the effectiveness of RSF processes in treating mine water from closed U mines.

Human walking biomechanics on sand substrates of varying foot sinking depth.

Our current understanding of human gait is mostly based on studies using hard, level surfaces in a laboratory environment. However, humans navigate a wide range of different substrates every day, which incur varied demands on stability and efficiency. Several studies have shown that when walking on natural compliant substrates there is an increase in energy expenditure. However, these studies report variable changes to other aspects of gait such as muscle activity. Discrepancies between studies exist even within substrate types (e.g. sand), which suggests that relatively 'fine-scale' differences in substrate properties exert quantifiable influences on gait mechanics. In this study, we compare human walking mechanics on a range of sand substrates that vary in overall foot sinking depth. We demonstrate that variation in the overall sinking depth in sand is associated with statistically significant changes in joint angles and spatiotemporal variables in human walking but exerts relatively little influence on pendular energy recovery and muscle activations. Significant correlated changes between gait metrics are frequently recovered, suggesting a degree of coupled or mechanistic interaction in their variation within and across substrates. However, only walking speed (and its associated spatiotemporal variables) correlate frequently with absolute foot sinkage depth within individual sand substrates, but not across them. This suggests a causative relationship between walking speed and foot sinkage depth within individual sand substates is not coupled with systematic changes in joint kinematics and muscle activity in the same way as is observed across sand substrates.

New status of Bichromomyia subspecies (Diptera: Psychodidae: Phlebotominae) based on molecular taxonomy.

The sand fly of the genus Bichromomyia (Galati, 1995) includes 3 subspecies considered vectors of Leishmania, which share high morphological similarity. Through information from the Cytochrome Oxidase Subunit I (COI) gene, we provide complementary evidence to support that Bichromomyia olmeca olmeca, and Bichromomyia olmeca bicolor, should be raised to nominal species status. We recovered specimens of Bi. o. olmeca from Quintana Roo, Tabasco, and Oaxaca, Mexico, supply 17 new COI sequences, and also incorporate GenBank sequences for other Bichromomyia species. After a Maximum Likelihood (ML) analysis, all Bichromomyia species clustered with a bootstrap of 100%, although sequences of Bichromomyia flaviscutellata were divided into 2 clusters with an interspecific range distance of 11.16% between them, which confirm cryptic species in Brazil. The genetic distance of Bi. o. olmeca compared to related subspecies ranged between 12.59% and 14.64%. A total of 29 haplotypes (Hd = 0.987; π = 0.08783; S = 136) were recovered from the Bichromomyia sequences. Results of the TC network were consistent with the ML analysis, supporting that subspecies of Bichromomyia are genetically distinct and deserve being raised to valid species category: Bichromomyia olmeca (Vargas & Díaz-Nájera) and Bichromomyia bicolor (Fairchild & Theodor).

Impact of sample refrigeration and freezing on the bacteriological counts of different bedding materials for dairy cows.

BACKGROUND: Different organic and inorganic bedding materials can be used in dairy farms. Among organic materials, there is an increasing interest in alternative substrates based on recycled manure solids (RMS). Microbiological analyses are crucial to monitor the microbial load and evaluate the presence of pathogens impacting animal welfare and health. However, logistic factors may hamper the possibility of immediately sending fresh samples to the laboratory, requiring storage in cooled conditions before analysis. METHODS: We assessed the impact of sample refrigeration and freezing of different organic and inorganic bedding substrates including separated raw manure solids (SRMS), anaerobically digested manure solids (ADMS), and new sand (NS), on the total bacterial count (TBC) and on different microbial classes. RESULTS: The TBC was higher in fresh NS and ADMS than in refrigerated and frozen samples of the same substrates; in addition, the TBC of ADMS was higher in refrigerated than frozen samples. The TBC of SRMS did not change significantly with refrigeration and freezing. Freezing reduced the total Gram-negative bacterial count more than refrigeration in all substrates. In fresh NS, Gram-negatives were higher than in both refrigerated and frozen NS. Escherichia coli counts were significantly lower in frozen than in refrigerated SRMS. However, both refrigeration and freezing of ADMS resulted in no E. coli growth. The coliform counts were also lower in frozen than refrigerated NS and SRMS. Frozen NS and ADMS showed lower counts compared to refrigeration for Gram-negative bacteria other than E. coli and coliforms. On the other hand, cold storage did not significantly impact the streptococci and streptococcus-like organisms (SSLO) count of all evaluated bedding substrates. CONCLUSION: Refrigeration and freezing affect the bacteriological results of bedding substrates, with freezing generally leading to lower counts than refrigeration. Whenever possible, preference should be given to analyzing fresh bedding samples, however, when necessary, refrigeration would be recommended over freezing, while acknowledging that the measured bacterial load might underestimate the actual microbial content.

Comparative Genomics Uncovers the Evolutionary Dynamics of Detoxification and Insecticide Target Genes Across 11 Phlebotomine Sand Flies.

Sand flies infect more than 1 million people annually with Leishmania parasites and other bacterial and viral pathogens. Progress in understanding sand fly adaptations to xenobiotics has been hampered by the limited availability of genomic resources. To address this gap, we sequenced, assembled, and annotated the transcriptomes of 11 phlebotomine sand fly species. Subsequently, we leveraged these genomic resources to generate novel evolutionary insights pertaining to their adaptations to xenobiotics, including those contributing to insecticide resistance. Specifically, we annotated over 2,700 sand fly detoxification genes and conducted large-scale phylogenetic comparisons to uncover the evolutionary dynamics of the five major detoxification gene families: cytochrome P450s (CYPs), glutathione-S-transferases (GSTs), UDP-glycosyltransferases (UGTs), carboxyl/cholinesterases (CCEs), and ATP-binding cassette (ABC) transporters. Using this comparative approach, we show that sand flies have evolved diverse CYP and GST gene repertoires, with notable lineage-specific expansions in gene groups evolutionarily related to known xenobiotic metabolizers. Furthermore, we show that sand flies have conserved orthologs of (i) CYP4G genes involved in cuticular hydrocarbon biosynthesis, (ii) ABCB genes involved in xenobiotic toxicity, and (iii) two primary insecticide targets, acetylcholinesterase-1 (Ace1) and voltage gated sodium channel (VGSC). The biological insights and genomic resources produced in this study provide a foundation for generating and testing hypotheses regarding the molecular mechanisms underlying sand fly adaptations to xenobiotics.

Transport and retention of COVID-19-related antiviral drugs in saturated porous media under various hydrochemical conditions.

Antiviral drugs have garnered considerable attention, particularly in the global battle against the COVID-19 pandemic, amid heightened concerns regarding environmentally acquired antiviral resistance. A comprehensive understanding of their transport in subsurface environments is imperative for accurately predicting their environmental fate and risks. This study investigated the mobility and retention characteristics of six COVID-19 antiviral drugs in saturated quartz sand columns. Results showed that the mobility of the drugs was primarily contingent on their hydrophobicity, with ribavirin and favipiravir exhibiting the highest transportability, while arbidol displaying the greatest retention. The transport characteristics of ribavirin and favipiravir remained largely unaffected by pH, whereas the retention of the other four antivirals remained consistently minimal under alkaline conditions. Elevating ionic strength marginally facilitated the transport of these antivirals, while the presence of Ca2+ notably enhanced their retention in quartz sand compared to Na+. Ribavirin and remdesivir warrant particular attention due to their relatively high transportability and propensity for environmentally acquired antiviral resistance. These findings contribute to an enhanced understanding of the leachate potential and transport of COVID-19-related antivirals in sandy porous media, furnishing fundamental data for predicting their environmental fate and associated risks.

An improved sand cat swarm optimization with lens opposition-based learning and sparrow search algorithm.

The sand cat swarm optimization (SCSO) is a recently proposed meta-heuristic algorithm. It inspires hunting behavior with sand cats based on hearing ability. However, in the later stage of SCSO, it is easy to fall into local optimality and cannot find a better position. In order to improve the search ability of SCSO and avoid falling into local optimal, an improved algorithm is proposed - Improved sand cat swarm optimization based on lens opposition-based learning and sparrow search algorithm (LSSCSO). A dynamic spiral search is introduced in the exploitation stage to make the algorithm search for better positions in the search space and improve the convergence accuracy of the algorithm. The lens opposition-based learning and the sparrow search algorithm are introduced in the later stages of the algorithm to make the algorithm jump out of the local optimum and improve the global search capability of the algorithm. To verify the effectiveness of LSSCSO in solving global optimization problems, CEC2005 and CEC2022 test functions are used to test the optimization performance of LSSCSO in different dimensions. The data results, convergence curve and Wilcoxon rank sum test are analyzed, and the results show that it has a strong optimization ability and can reach the optimal in most cases. Finally, LSSCSO is used to verify the effectiveness of the algorithm in solving engineering optimization problems.

Enhancing the performance of paraffin's phase change material through a hybrid scheme utilizing sand core matrix.

Smart waste management and valorisation is presented in the current investigation. Iron is collected from mining wastewater stream and augmented with sand as a supporting material to produce sand core. The sand core pellets encapsulated in paraffin's to enhance its feasibility as phase change material (PCM). Sand core was characterized using X-ray diffraction and Scanning Electron Microscope (SEM) augmented with energy dispersive X-ray spectrum analysis. Experimental test is achieved by mixing sand core/iron and paraffin that is signified as an encapsulated phase change material. The encapsulated sand core-PCM is embedded in varies mass weights of percentages of 0.5, 1.0, 1.5 and 2.0% and labeled as 0.5%-sand core-PCM, 1.0%-sand core-PCM, 1.5%-sand core-PCM and 2.0%-sand core-PCM. The encapsulated sand core-PCM is embedded into a heat exchanger of the vertical type model that is connected with a flat plate solar collector. Such collector is heating the heat transfer carrier, which is exposed to the heat exchanger for melting the PCM. The experimental work is conducted across the solar noon where the solar intensity in the region is reached to 1162 W/m2 at the time of conducting experiments. Water is applied and supposed as the working heat transfer fluid transporter and pumped into the system at the rate of 0.0014 kg per second. The experimental result revealed that the heat gained recorded an enhancement from 7 to 48 kJ/min when the 1.5%-sand core-PCM system is applied. Thus, the results showed the system is a good candidate by increasing the system efficiency with 92% as a potential solution of solar energy storage at the off-time periods.

Ecosystem regime shifts and its application prospects to ecosystem management in cold and arid regions.

Ecosystem regime shifts refer to the drastically changes of an ecosystem from one state to another after suffering disturbances that exceed the thresholds. Although land desertification and grassland degradation, which are common in the cold and arid regions, are gradual processes, sudden changes can also occur when the duration or intensity of disturbances exceed the thresholds. Therefore, the study of ecosystem regime shifts is of great significance to the management of ecosystems in cold and arid regions. In this review, we summarized the evolution of ecosystem regime shift theory and early warning signals, and analyzed the problems of land desertification and grassland degradation in cold and arid regions, as well as potential responses of ecosystems to different stresses. We further put forward research frameworks for the evolution and mutation characteristics of the rain-fed artificial sand fixation system and alpine meadows. The future research needed to be strengthened in identifying the key drivers of ecosystem regime shifts at different stages, determining the corresponding thresholds, emphasizing the mechanism of water-limited mutation induced by extreme climatic events and its early warning, and promoting the application of regime shift research to ecosystem management in arid and arid regions.

The interaction of microplastic and heavy metal in bioretention cell: Contributions of water-soil-plant system.

The effectiveness of bioretention cells for heavy metals (HMs) and microplastics (MPs) removal from stormwater runoff has been demonstrated. Knowledge of the mechanisms that dictate the interactions between MPs and HMs would be helpful in pollution control. In this study, the performances of different water-soil-plant bioretention cells for HMs removal through the interception of polyethylene MPs (PE-MPs) were investigated. The results showed that PE-MPs bound to HMs and preferentially tended to bind to Pb (32%-44%) in the complex HMs (Cu, Zn, Cd, and Pb). This could be the reason that the concentration of Pb significantly increased in the effluent under low-intensity simulated rainfall events over a long duration. The accumulation of 1.49 g/kg PE-MPs caused a significant soil pH value decrease and a notable soil zeta potential increase in the bioretention cell, while the low sand/silt ratio media buffered this process. The retention of PE-MPs increased 138.5% in the 0-10 cm soil surface layer when the sand/silt ratio reduced from 2:1 to 1:1 and planted with Canna indica. Meanwhile, PE-MPs amplified the instability of Zn removal in bioretention cells under low-intensity rainfall events in long-duration, high silt percentage substrate and vegetation coverage. The study would contribute to developing a long-term management program for PE-MPs and HMs trapped in bioretention cells to reduce the risk of pollution transport.