Suspended Particles Research Articles

Detailed comparison of recent—and dissimilar—effective-medium models incorporating dependent scattering

We compare the predictions of two recently derived effective-medium models for the effective refractive index of a turbid suspension of particles. The two formulas are notoriously dissimilar; both are based on the quasi-crystalline approximation, but the approximations used beyond this point are entirely different. Nevertheless, for dilute suspensions both reduce to the well-established van de Hulst formula. The dissimilarities between the formulas are evident for dense suspensions, where dependent-scattering effects are important. When they might coincide is, therefore, not clear. The purpose of this work is to explore the range of particle parameters and volume fractions for which both models are applicable. Our results show that, rather surprisingly, the models produce very similar curves of the real and imaginary parts of the effective refractive index for volume fractions up to 0.4 and for particles comparable to, and larger than, the wavelength, as well as for a fairly large range of refractive-index contrasts between the particles and the surrounding medium. These results significantly increase our confidence in the validity of both models.

Study on the diffusion and blocking behavior of bubble plumes in Cross-Flow

Abstract With the deepening of the concept of environmental protection, environmental problems in dredging engineering have attracted more and more attention. The diffusion of suspended particulate matter is inevitable in the process of dredging. A bubble plume, as a multiphase linear plume, has been widely studied because it can block the diffusion of suspended particulate matter in water. To explore the formation characteristics of the bubble plume, we evaluate the formation quality of the bubble plume qualitatively and quantitatively, analyze the effect of the bubble plume on blocking the diffusion of suspended particulates under different operating conditions (the type of bubble plume generation device, the number of bubble plume rows, and the ventilation flow rate) and environmental conditions (water flow velocity), and study the movement trajectory of blocked particles and blocked failed particles. A series of experiments on bubble plume characteristics and bubble plume blocking the diffusion of suspended particles were conducted to analyze the particle distribution characteristics and bubble plume blocking effect under the interaction of transverse flow and bubble plume. The results show that the better the quality of the bubble plume is, the lower the transverse flow intensity is, and the better the barrier effect of the bubble plume is.

Temporal and spatial distribution of novel brominated flame retardants in atmosphere of the Beijing-Tianjin-Hebei region, China

The occurrence and spatio-temporal distribution of atmospheric novel brominated flame retardants (NBFRs) were studied across five sampling sites in the Beijing-Tianjin-Hebei (BTH) region over a whole year. By collecting samples (gas and particle) with a high-volume active air sampler (HV-AAS), nine NBFRs were analyzed and the sum concentrations ranged from 1.65 to 344 pg/m3, with the highest value found in the urban sampling site in Shijiazhuang City. Decabromodiphenylethane (DBDPE) was the predominant congener, which accounted for 60% of ∑9NBFRs on average, while it was 90% of ∑9NBFRs in the rural site and significantly higher than those observed in the urban sites (one-way ANOVA, p < 0.05). The levels of particle-bound NBFRs were significantly correlated with the variation of total suspended particulates (TSP) and temperature (p < 0.01), indicating their evident impact on the spatio-temporal distribution of NBFRs. Moreover, a significantly positive correlation was observed between the concentrations of 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB) and bis (2-ethyl-1-hexyl) tetrabromophthalate (BEH-TEBP) (p < 0.01). Monocyclic brominated flame retardants (including PBBz, PBT, PBEB, HBB and TBP-DBPE) were correlated with each other (p < 0.01) in both gas and particle phase, suggesting their co-occurrence and the similar source in the environment. The gas-particle partitioning behavior was well predicted by the Li-Jia Empirical Model, and the results indicated that the target NBFRs did not reach the equilibrium state in air. This is one of very few studies revealed the spatio-temporal distribution of atmospheric NBFRs in the BTH region.

Integrating physical and biogeochemical processes and oceanic exchanges at a coastal lagoon in Southern West Europe

Coastal lagoons are highly productive systems and the quantification of mass fluxes, which is of paramount importance for the sustainable management of these systems, remains poorly studied. In this context, a detailed study was conducted to better understand the exchanges between the productive coastal lagoon Ria Formosa (South-West Europe) and the ocean. The exchanges of water, nutrients, chlorophyll-a and suspended solids between the main inlets (Faro-Olhão inlet - BFO; Armona inlet - BAR; and Ancão inlet - BAN) and adjacent channels (Faro - CF and Olhão - CO) and the adjacent ocean were estimated along complete semidiurnal tidal cycles, under extreme fortnightly tidal ranges and different seasonal and environmental/oceanographic conditions. The net tidal prism was highest during spring tides. Among the three inlets, BFO was the most important in terms of exchange, followed by BAR and BAN. Net transport at BFO was lowest during the Summer campaign, although it exported material that fertilised the adjacent coast. The persistent net export of suspended solids and ammonium suggests the higher biological productivity of Ria Formosa compared to that found in coastal waters. In the Winter campaign, after a period of rainfall and increased land runoff, there was a remarkable export of matter, on which, ammonium and suspended particles exported can exceed 0.3 times and almost 0.9 times, respectively, those imported from coastal water. However, the import of phosphate and nitrate can be attributed to a weak coastal upwelling event, as well to low consumption and nitrification at this period of low temperature. During the Spring and Autumn campaigns, the Ria Formosa was fertilised either by upwelling events or due to rapid consumption of nutrients by phytoplankton in this shallow system. BFO and the other two inlets of the western sector of Ria Formosa are interconnected by CF and CO. The higher nutrient transport was recorded at CF, despite the highest nutrients concentrations was recorded at CO. The data show the strong link between physical and biogeochemical processes with meteorological/oceanographic factors. The study showed that associated biological processes are superimposed on the tidal effect in this system. Data from this study could be used as a reference, particularly important for management of Ria Formosa, a productive system where bivalves production depends deeply on water quality. In addition, the nutrient concentrations and mass exchanges resulting from the different processes can be used as a reference for other lagoon systems where shellfish production is practised.

Assessment of the water quality in the coastal Yaqui valley (Mexico): implications for human health and ecological risks.

This study examines the water quality in the Yaqui Valley in Mexico, a semi-arid region impacted by mining, agriculture, and aquaculture. Contamination sources, health risks and ecological impacts are investigated. Freshwater was found to be contaminated by dissolved As, presumed to result from mining activities in the mountains. Drainage water revealed an overall contamination by dissolved As and by suspended particles enriched with Al, Fe and Mn, associated with runoff processes. Intermittent contamination of drainage water by Cu, K+, NO3- and PO43- is attributed to the use of fertilizers or pesticides. In the coastal area, drainage water contains high concentrations of Na, Ca, SO42- and Cl, related to salinization processes, as well as higher concentrations of dissolved As, related to solid/liquid interactions that are enhanced by salinization. This drainage water discharges into the bay, degrading the seawater quality and increasing ecological risks. Outputs of this study can serve as a reference for the protection of this economically important coastal ecosystem. Concerning health risks, this study demonstrates that groundwater is also contaminated by dissolved As, believed to be associated with transfers from the geological basement to the dissolved phase of water, and other major chemicals related to salinization processes. The findings indicate that ingesting the groundwater poses a significant risk to human health with a primary exposure risk associated with dissolved As, particularly among children. This study presents crucial data for the Yaqui population, water managers and researchers, and provides novel insights into the management and mitigation of the identified risks.

Evaluation of protein-polysaccharide interactions through ζ-potential and particle size measurements to assess their functionality in wine.

Protein-polysaccharide-tannin interactions are important in every aspect of red wine production from physical stability to color, astringency, and body. For this model study, bovine serum albumin (BSA) was selected as the protein, while carboxymethyl cellulose (CMC), mannoproteins, and pectin were the model polysaccharides. Each protein-polysaccharide combination was analyzed for zeta (ζ) potential and particle size at neutral pH and within the wine-like solution. Mixtures were assessed regarding their protective, affinitive, and aggregative behaviors. Based on their individual ζ-potentials, pectin and mannoprotein were most stable at lower concentrations. At higher concentrations, they reduced the suspension's stability and increased the aggregate sizes. CMC consistently increased the stability of any solution under neutral pH conditions. However, with increasing concentrations, these large aggregates are expected to precipitate. Fruit pectin (FP) and BSA interactions seemed to be the main factors in the formation of visible precipitates at neutral pH. FP and the mannoprotein decreased stability enough to cause precipitation without haze formation. The mannoprotein decreased particle sizes, in both the suspension and precipitation, which may indicate greater selectivity toward proteins. FP also decreased the suspended particle sizes under wine conditions. These findings demonstrate the use of ζ-potential and particle size values to characterize macromolecular interactions in model systems and can also be used to indicate effective fining agents. PRACTICAL APPLICATION: This work demonstrates the capabilities of ζ-potential analysis paired with size particle measurements to predict and characterize the interactions between macromolecules in complex systems. The interactions between model wine macromolecules can be evaluated with this technology at a level that cannot be reached with any other analytical technique.

Injectability of high concentrated suspensions using model microparticles

Administration of high-concentrated suspension formulations (i.e., solid particles dispersed in a liquid vehicle) can be limited due to their greater propensity for needle occlusion. The physical interaction between the solid phase (i.e., particles), the vehicle (i.e., flow field), and injection devices could result in the formation of particle bridging or filtering, posing a major risk in dose delivery accuracy and injectability. Here, given the limited understanding on how clogging initiates in syringe and needle delivery systems, we report an experimental approach to fully characterize the transient injection behavior of suspensions. In particular, we first established a custom fluorescence tagging and imaging technique with integrated force sensor to enable visual observation of local particle concentrations and plunger force monitoring throughout injection. Then, we investigated the effects of key formulation properties and device parameters including particle concentration and morphology, carrier viscosity, injection rate, needle and syringe sizes, and tissue backpressure on the incidence of suspension particle jamming and needle clogging. We performed systematic benchmark studies demonstrating that increasing needle inner diameter (ID) and particle density considerably reduced clogging risk, while increasing vehicle viscosity, particle size, and tissue backpressure significantly increased clogging. The experimental framework presented is amenable to quantifying clogging risk in drug-loaded particle suspensions and provides a guideline to make informed decisions on the tradeoffs between creating particles for pharmaceutical impact and feasibility of injection delivery.

Particle Concentrations and Sizes for the Onset of Settling‐Driven Gravitational Instabilities: Experimental Validation and Application to Volcanic Ash Clouds

AbstractSettling‐driven gravitational instabilities (SDGIs) can form at the base of buoyant particle‐laden suspensions, modulating particle sedimentation in various settings such as meteorological and volcanic clouds, fluvial plumes, magma chambers, submarine hydrothermal plumes, or industrial emissions. These instabilities result in the formation of rapidly descending currents called ‘fingers’ within which fine particles settle faster collectively than individually. This study investigates SDGI triggering conditions underneath volcanic ash clouds through analogue experiments considering sedimentation from aqueous particle suspensions. We confirm that the conditions for which SDGIs develop are controlled by two dimensionless numbers: Bf (ratio of the characteristic finger velocity to the individual particle settling velocity); and Bi (ratio of timescale for individual particle settling to that for collective settling controlled by inertial drag). SDGIs are triggered for values of Bf and Bi &gt; 1 for which particles are fully coupled with the flow within fingers. Using these parameters, we produce a regime diagram for the 2010 eruption of Eyjafjallajökull (Iceland) that describes particle settling as a function of particle concentration and size. More studies are needed to produce a general regime diagram accounting for the evolution of SDGIs properties with eruption and atmospheric parameters. Nonetheless, our study confirms that fingers affect sedimentation from volcanic clouds with high ash volume fractions above 10−6 vol.%. Our validation of criteria predicting the onset of fingers due to SDGIs constitutes a step forward toward the incorporation of these collective settling processes in volcanic ash transport and dispersion models.

Climatic Impact on the Air Pollutant Concentrations Emitted from Gas Stations in Fallujah, Al-Anbar, Western Iraq

The research investigates the influence of climatic elements like temperature, relative humidity, rainfall, evaporation, dust storms, wind direction, and speed on the air pollutant concentrations at gas stations in Fallujah city while examining their impact on humans and the environment. This was achieved by measuring concentrations of CO, NO2, and CH4, suspended particles (TSP, PM10), and Cu, and Pb. It was found that the impact increased in July compared to January, because of the influence of the measured climatic elements. Rising temperatures increase air pollutants' concentrations in the atmosphere, while winds spread them from emission sites to distant locations. Moreover, summer temperatures significantly impacted air pollutant concentrations at the study stations, particularly at Al-Rehab gas station, with the highest recorded temperatures of 48.4°C. Some gas stations also exceeded local environmental limits for TSP, PM10, CO, NO2, and Pb. The study revealed that summer temperatures with wind speeds of 2.1 m/s resulted in the highest air pollutants values, while winter temperatures with wind speeds of 1.9 m/s decreased these values. Higher temperatures increase chemical reactions and temperature inversions, leading to increased pollution concentrations and exacerbating air quality problems in the study area. Strong winds disperse pollutants, reducing concentration in the study area, while low wind speed increases concentrations and stagnation, resulting in poor air quality in the studied sites. The importance of the current study lies in evaluating pollutants in the Fallujah city, determining their causes, the extent of the impact, and contribution of natural and human sources in causing changes in air pollutant concentrations; caused by emission from the source. Moreover, the current study showed its impact on human’s health, and trying to find solutions to limit these effects or reduce their levels to ensure the safety of the environment and health.

Primary Study on Influence of Conventional Hydrochemical Components on Suspension of Endogenous Fine Loess Particles in Groundwater over Loess Regions

To ascertain the effects of conventional hydrochemical components on the presence of endogenous fine loess particles (EFLPs) in groundwater over loess regions, Na+, NO3− and Cu2+, as conventional hydrochemical components, were employed in batch tests with EFLPs from a typical loess as aquifer media in Guanzhong Plain, China. The results showed that EFLPs had high zeta potential (ζ) and remained suspended over 40 h, indicating their good dispersity and potential to be suspended in groundwater. ζ was employed to replace electrostatic repulsion in the DLVO equation to determine the critical coagulation concentrations for Cu(NO3)2 and NaF as 0.1 mmol/L and 50 mmol/L for 1.1 µm D50 EFLPs, which were almost consistent with the batch test results and greater than those in the groundwater, respectively, further implying that EFLPs are likely to be suspended in groundwater. The multi-factor tests showed that the key factors including particle size, hydro-chemical component and concentration interacted with each other and their relative magnitudes varied in the test processes, where the effects of concentration strengthened while those of the component weakened. So, hydrogeochemical conditions were beneficial to the suspension of EFLPs and the benefit got strong along the groundwater flow path, which is conducive to the cotransport of EFLPs with pollutants in groundwater over loess regions.

COPOLYMER BASED ON [(3-METHACRYLOYLAMINO)PROPYL] TRIMETHYLAMMONIUM CHLORIDE AS A FLOCCULANT FOR INDUSTRIAL WATER TREATMENT

The using of polymeric flocculants in the development of the oil industry in Kazakhstan is one of the innovative tasks. Therefore, the creation of new effective flocculants based on available industrial monomers with structure-forming is an urgent task. The mechanism of action of flocculants is based on the phenomenon of adsorption of flocculant molecules on the surface of colloidal particles, the formation of a network structure of flocculant molecules, and the adhesion of colloidal particles due to van der Waals and other forces. New polymeric flocculant with different molar composition was synthesized by radical copolymerization [(3-methacryloylamino)propyl]trimethylammonium chloride (TMAPMACh) with N,N-dimethyl-acrylamide (DMAA) at 333 K in the presence of ammonium persulfate, (NH4)2S2O8 as an initiator. The molar composition of the synthesized TMAPMACh-DMAA copolymer was determined by FTIR and NMR spectroscopy and conductometric titration with AgNO3 solution. The flocculation properties of the copolymers were studied by measuring the sedimentation of dispersed particles of bentonite suspension in the presence of the flocculant. Sedimentation degree was determined by measuring the optical density of the suspension. It was found that TMAPMACh-DMAA copolymers had a flocculating effect and could be used for industrial wastewater treatment. Thermogravimetric analysis showed that this copolymer was thermally stable up to 270°C. Therefore, it can be used in deep well drilling to regulate the properties of drilling fluids.

Chemistry and Physics of Wet Foam Stability for Porous Ceramics: A Review

The unique structural properties of porous ceramics, such as low thermal conductivity, high surface area, controlled permeability, and low density, make this material valuable for a wide range of applications. Its uses include insulation, catalyst carriers, filters, bio-scaffolds for tissue engineering, and composite manufacturing. However, existing processing methods for porous ceramics, namely replica techniques and sacrificial templates, are complex, release harmful gases, have limited microstructure control, and are expensive. In contrast, the direct foaming method offers a simple and cost-effective approach. By modifying the surface chemistry of ceramic particles in a colloidal suspension, the hydrophilic particles are transformed into hydrophobic ones using surfactants. This method produces porous ceramics with interconnected pores, creating a hierarchical structure that is suitable for applications like nano-filters. This review emphasizes the importance of interconnected porosity in developing advanced ceramic materials with tailored properties for various applications. Interconnected pores play a vital role in facilitating mass transport, improving mechanical properties, and enabling fluid or gas infiltration. This level of porosity control allows for the customization of ceramic materials for specific purposes, including filtration, catalysis, energy storage, and biomaterials.

Wildfire Particulates Enhance Phytoplankton Growth and Alter Communities in the South China Sea Under Wind‐Driven Upwelling

AbstractExtreme wildfire events and cyclones are on the rise across tropical regions in response to climate change. Despite assumptions about their impact on phytoplankton through nutrient supplies, field evidence is lacking, and their combined effects remain unclear. In an on‐site microcosm experiment conducted in the Xisha Islands, South China Sea (SCS) after Typhoon Noru, we observed enhanced phytoplankton growth in response to exposure to total suspended particulates (TSP) from wildfires (2 mg/L and 6 mg/L) under wind‐driven upwelling conditions. Upwelled nutrients had a limited effect on Chl‐a concentration due to phosphate depletion, by contrast, wildfire TSP contributed nutrients enriched in nitrogen and phosphate, resulting in a 3.30–5.61‐fold increase in Chl‐a. However, upwelled nutrients increased the diatom‐to‐dinoflagellate ratio from the initial 11.0 to 12.7, TSP at low and high levels reduced the ratio to 0.3–0.8 and significantly altered the communities, with 61.8% of species, including two dominant diatoms, negatively correlated with N and/or P supplies. Species diversity declined significantly at high TSP levels. These findings suggest that enhanced primary productivity by wildfires may come at the cost of an altered phytoplankton community. This field study improves understanding of the effects of simultaneous occurrences of multiple extreme climate events on marine ecosystems.

Study of patterns of PM2.5 and PM10 changes in the atmospheric air of Ivano-Frankivsk region

The purpose of this research is to analyse the temporal patterns of changes in concentrations of dust particles – aerosols, regression modeling of the interdependence of PM2.5 and PM10 at the level of instantaneous, average hourly, average daily and average weekly concentrations, and assessment of the impact of the anthropogenic component of dust pollution of atmospheric air in the Ivano-Frankivsk region on regularities of the temporal distribution of these shares.The database for the study included measurements of the concentration of PM10, PM2.5 every hour at four Ecocity public monitoring stations: in the central part of the city of Ivano-Frankivsk, in the village of Bovshiv within the influence of the Burshtyn TPP, in the village of Broshniv-Osada within the influence of the woodworking enterprise "SVISS KRONO" and within the recreational territory of the village of Mykulychyn, Nadvirnyan district. The general regularity of the temporal distribution of PM10, PM2.5 was established for all posts for daily fluctuations – the highest concentrations are observed at night, the lowest – during the period of maximum daily temperatures. It has been proven by actual data that the greater the level of atmospheric air pollution (the greater the anthropogenic component of PM), the higher the daily concentrations of PM10, PM2.5 and the more often the one-time standards of solid suspended particles are exceeded.According to the data of monitoring stations from the territories with different anthropogenic influence, functional dependences of PM2.5 content on PM10 content were obtained for instantaneous values, hourly average values, daily average values, and weekly average values. The scientific novelty of the conducted research consists in the establishment of identical functional interdependence of temporal changes in concentrations of PM2.5 and PM10 dust particles within a conditionally clean area and within the limits of the influence of stationary sources of pollution with a high level of direct regression dependence and a coefficient of determination greater than 0.9 in all cases. This allows us to conclude that the temporal patterns of changes in both PM2.5 and PM10 will not differ in clean and polluted air conditions for the Ivano-Frankivsk region. In conditions of incomplete data on the temporal distribution of the concentration of PM10, the obtained equations can be used to forecast the temporal distribution of the concentration of PM2.5.

Photodegradation of polychlorinated biphenyls (PCBs) on suspended particles from the Yellow River under sunlight irradiation: QSAR model and mechanism analysis

Polychlorinated biphenyls (PCBs), as a class of hydrophobic organic pollutants, are widely found in river sediments and suspended particles, and the environmental fate of different PCBs can be better understood by investigating their photochemical transformation process. In this study, the quantitative structure-activity relationship (QSAR) model between the photodegradation rate constants of 17 PCBs adsorbed on Yellow River suspended particles in water (as a typical heterogeneous photodegradation system) and the physicochemical parameters of PCBs was constructed by SPSS and machine learning. The model showed that the more hydrophobicity of the molecule, the more positive charge carried by the aromatic C atoms, and the presence of chlorine atoms adjacent to the carbon bridge could all enhance the photochemical activity of PCBs. From the combined analysis of rate constants, quenching experiments and theoretical calculations, it was revealed for the first time that in natural suspended particle containing organic matter, the higher concentration of •O2- and 1O2 in the hydrophobic zone contributed more to the more hydrophobic PCBs, while •OH in the hydrophilic zone played a major role in the degradation of the less hydrophobic PCBs. Findings of this study would deepen the understanding of the degradation mechanism of hydrophobic pollutants by active species in complex environments.

Contrasting but interconnecting metatranscriptome between large buoyant and small suspended particles during cyanobacterial blooming in the large shallow eutrophic Taihu Lake

Large cyanobacterial colonies as visible particles floating on the water surface provide different microbial niches from small particles suspended in the water column in eutrophic freshwaters. However, functional potential differences among microbes colonizing on these contrasting particles are not well understood. Here, the metatranscriptome of microbes inhabiting these two kinds of particles during cyanobacterial bloom (dominated by Microcystis spp.) was analyzed and compared. Community compositions of active bacteria associated with small suspended particles (SA, aggregates dominated by small cyanobacteria colonies, other algae and detritus, etc.) were much more diverse than those associated with large buoyant cyanobacterial colonies (LA), but functional diversity was not significantly different between them. Transcripts related to phosphorus and nitrogen metabolism from Proteobacteria, and respiration from Bacteroidetes were enriched in LA, whereas many more pathways such as photosynthesis from Cyanobacteria, cofactors, and protein metabolism from all dominant phyla were enriched in SA. Nevertheless, many transcripts were significantly correlated within and between LA and SA. These results indicated interconnection of bacteria between LA and SA. Moreover, many transcripts in SA were significantly correlated with transcripts from cyanobacterial phycobilisome in LA, indicating that bacterial metabolism in SA may influence cyanobacterial biomass in LA. Thus, the prediction of cyanobacterial blooms by bacterial activity in SA may be possible when there is no visible bloom on the water surface.

Fluorine-free superhydrophobic surfaces by atmospheric pressure plasma deposition of silazane-based suspensions

Atmospheric plasma is used to deposit superhydrophobic fluorine-free thin films onto a substrate. In this process, a suspension of micron size silica particles in a silazane based precursor is deposited in a single step using a dielectric barrier discharge plasma jet moving above the substrate. Thanks to an optimized configuration between the suspension injection and the plasma jet, the silazane precursor can be polymerized on the substrate surface but also, on silica particles to form additional micro size particles. The experimental parameters for optimal deposition are discussed, with emphasis on those leading to the formation of this dual roughness surface caused by the arrangement of both silica particles and particles generated from the precursor plasma polymerization. The combination of these two different length scales for the roughness leads to a decreased wettability of the coated substrate and a water contact angle larger than 150°.

Effect of instantaneous local solid volume fraction on hydrodynamic forces in freely evolving particle suspensions

Particle Resolved Simulations (PRS) for freely evolving sphere suspensions at solid volume fractions (φ) between 0.1 and 0.4, Reynolds number Re from 10 to 300 and particle-fluid density ratios ρsρf of 2, 10 and 100 are used to investigate the effect of Voronoi tessellation based particle local solid volume fraction (φv)on particle drag and lateral forces. Findings reveal the instantaneous suspension mean drag force is positively correlated with the variance of φv among particles in the suspension. It is also shown that using the conditioned instantaneous φv of each particle in existing mean drag force correlations can significantly improve the prediction accuracy. Suspension mean lateral force ranges up to 60 % of the drag force while individual particles exhibit values as high as 90 % of the drag force. An instantaneous lateral force correlation is proposed based on suspension-averaged flow variables and φv.

Highly Porous Particles of Cellulose Derivatives for Advanced Applications.

A chemical modification of cellulose diacetate by phthalate and nitrate was performed to increase solubility in organic solvents and change the electrical properties. The role of substituents on the conductivity, permittivity, and polarizability of cellulose films is revealed. It has been shown that highly porous micro particles can be obtained from cellulose derivatives by a simple and technological freeze-drying method. The resulting micro sized aerogels have a predominantly spherical morphology and amorphous structure. Suspensions of porous particles of nitro- and phthalylated cellulose derivatives in silicone oil have an increased dielectric permittivity compared to cellulose diacetate particles. Produced particles are novel promising material with tunable electrical properties for advanced applications in composites, including for electrorheological fluids.

Co-analysis of total suspended particles and discharge reveals the dynamic of mercury input into glacier meltwater runoff in the northern Tibetan Plateau

Climate warming has accelerated glacier melting, releasing legacy pollutants such as mercury (Hg) into aquatic ecosystems. While the relationship between Hg in glacier meltwater runoff, total suspended particles (TSP), and runoff discharges has been established, the underlying inter-relationships and governing factors remain poorly understood. To address this knowledge gap, we conducted a continuous fixed-point sampling at Laohugou No. 12 Glacier in the northern Tibetan Plateau from June to September 2019 spanning the entire glacier ablation season. Our study analyzed the variations of Hg partition in the meltwater runoff and conducted a comprehensive co-analysis of Hg with TSP and discharge to uncover the dominant factors of Hg input into meltwater runoff. The concentration of total Hg (THg) in the meltwater runoff ranged from 0.7 to 112.6 ng/L, with an average concentration of 26.6 ± 25.1 ng/L. Particulate Hg (PHg) was found to be the predominant partition, while dissolved Hg (DHg) exhibited a notable increase in June and September. THg concentration significantly correlated with TSP concentration (r = 0.94, P < 0.01), exceeding the correlation with discharge (r = 0.76, P < 0.01) during the entire ablation period. However, further examination during varying hydrological periods revealed differing associations among Hg speciation concentrations, TSP concentration, and discharge. During the rising limb of the hydrograph, THg (r = 0.86, P < 0.01) and PHg concentrations (r = 0.87, P < 0.01) exhibited a significant correlation with TSP concentration, primarily driven by TSP, implying that Hg availability determines the Hg input into meltwater runoff. Conversely, during the recession limb of the hydrograph, THg concentration was primarily influenced by discharge (r = 0.85, P < 0.01). PHg (r = 0.84, P < 0.01) and TSP (r = 0.97, P < 0.01) concentrations were strongly influenced by discharge, indicating that hydraulic action is the dominant factor affecting Hg input. Our study elucidated the impact of glacier hydrological processes on Hg transport, revealing the dominant factors of Hg input during different hydrological periods. This contributes to a deeper understanding of Hg input into meltwater runoff and improves predictions of Hg export through glacier melt in high mountain regions.