Varying Particle Size Research Articles

Cytotoxicity and Antimicrobial Efficacy of Fe-, Co-, and Mn-Doped ZnO Nanoparticles

Zinc oxide nanoparticles (ZnO NPs) are one of the most widely used nanoparticulate materials due to their antimicrobial properties. However, the current use of ZnO NPs is hindered by their potential cytotoxicity concerns, which are likely attributed to the generation of reactive oxygen species (ROS) and the dissolution of particles to ionic zinc. To reduce the cytotoxicity of ZnO NPs, transitional metals are introduced into ZnO lattices to modulate the ROS production and NP dissolution. However, the influence of the doping element, doping concentration, and particle size on the cytotoxicity and antimicrobial properties remains unexplored. This study presents a comprehensive investigation of a library of doped ZnO NPs to elucidate the relationship between their physicochemical properties, antimicrobial activity against Escherichia coli (E. coli), and cytotoxicity to mammalian cells. The library comprises 30 variants, incorporating three different dopant metals—iron, manganese, and cobalt—at concentrations of 0.25%, 1%, and 2%, and calcined at three temperatures (350 °C, 500 °C, and 600 °C), resulting in varied particle sizes. These ZnO NPs were prepared by low temperature co-precipitation followed by high-temperature calcination. Our results reveal that the choice of dopant elements significantly influences both antimicrobial efficacy and cytotoxicity, while dopant concentration and particle size have comparatively minor effects. High-throughput UV–visible spectroscopic analysis identified Mn- and Co-doped ZnO NPs as highly effective against E. coli under standard conditions. Compared with undoped ZnO particles, Mn- and Co-doping significantly increased the oxidative stress, and the Zn ion release from NPs was increased by Mn doping and reduced by Fe doping. The combined effects of these factors increased the cytotoxicity of Mn-doped ZnO particles. As a result, Co-doped ZnO particles, especially those with 2 wt.% doping, exhibited the most favourable balance between enhanced antibacterial activity and minimized cytotoxicity, making them promising candidates for antimicrobial applications.

Influence of Composition on the Patterns of Electrokinetic Potential of Thermosensitive N-(Isopropyl)Acrylamide Derivatives with Poly(Ethylene Glycol) Dimethacrylate and N-(2-Hydroxyethyl)Acrylamide

The synthesis of poly(N-isopropyl acrylamide) (pNIPA)-based polymers via the surfactant-free precipitation polymerization (SFPP) method produced thermosensitive nanospheres with a range of distinctive physicochemical properties. Nano- and microparticles were generated using various initiators, significantly influencing particle characteristics, including the hydrodynamic diameter (DH), which varied from 87.7 nm to 1618.1 nm. Initiators, such as potassium persulfate and 2,2′-azobis(2-methylpropionamidine) dihydrochloride, conferred anionic and cationic functionalities, respectively, impacting the electrokinetic potential (EP) of the particles. Notably, certain particles with cationic initiators exhibited negative EP values at 18 °C, attributed to residual initiator components that affected the surface charge distribution. The presence of hydrophilic N-(2-hydroxyethyl)acrylamide (HEAA) segments also influenced solubility and phase transition behaviors, with critical dependencies on the HEAA/NIPA (N-isopropyl acrylamide) molar ratios. EP measurements taken at 18 °C and 42 °C revealed substantial differences, primarily governed by the initiator type and polymer composition. Observed variations in particle stability and size were associated with the choice of crosslinking agents and comonomer content, which affected both DH and EP in distinct ways. This study provides insights into key factors influencing colloidal stability and electrostatic interactions within thermosensitive polymer systems, underscoring their potential applications in biomedical and industrial fields.

Date Palm Waste-Derived Biochar for Improving Hydrological Properties of Sandy Soil Under Saturated and Unsaturated Conditions

Water conservation and effective irrigation management are vital for sustainable agriculture in arid regions. While organic soil amendments have been widely used to enhance water retention in sandy soils, research on the use of date palm waste-derived biochar remains limited. Thus, this study aimed to explore the innovative application of biochar produced from date palm waste, focusing on its effects on the hydrological properties of sandy soil. Biochars of varying particle sizes (0.5, 1, and 2 mm) and pyrolysis temperatures (300 °C, 450 °C, and 600 °C) were produced and their impacts were assessed under both saturated and unsaturated conditions on soil hydrological properties. The biochar was incorporated into soil columns at application rates of 0%, 1%, 3%, and 5% (w/w) within a 10 cm layer on top of 35 cm deep soil columns. The soil columns were placed vertically into water basins for saturation. Evaporation, infiltration, and saturated hydraulic conductivity were measured. The findings revealed that the application of 1%, 3%, and 5% biochar significantly increased soil water retention by 36.80%, 34.18%, and 29.66%, while cumulative evaporation decreased by 7.30%, 2.00%, and 1.35%, respectively, as compared to the control. Water retained at the end of the experiment was increased by 100.63%, 112.29%, and 101.68%, while unsaturated hydraulic conductivity decreased by 21.27%, 26.15%, and 26.17% after amending the soil with 1%, 3%, and 5% biochar, respectively, as compared to the control. The water retention ranged between 30.34 and 42.51%, 22.59 and 43.20%, and 22.48 and 38.81% for biochar produced at 300 °C, 450 °C, and 600 °C, respectively. Water infiltration rate and pore size was decreased with the increased pyrolysis temperature. Overall, the application rates of 3% and 5% with particle sizes of 1 and 0.5 mm and low pyrolysis temperature were most efficient for improving soil properties such as water retention, reducing unsaturated hydraulic conductivity, reducing the rate and volume of infiltration, and enhancing the micro-porosity reduction of sandy soils. In a nutshell, this study highlights the potential of date palm waste-derived biochar as an effective soil amendment, significantly enhancing water retention by up to 112.29% and reducing evaporation. By optimizing irrigation management in sandy soils, these findings contribute to more sustainable agricultural practices.

Thermoplastic Composite Hot-Melt Adhesives with Metallic Nano-Particles for Reversible Bonding Techniques Utilizing Microwave Energy

This study investigated the creation of nano-composites using recycled LDPE and added 7.5 wt% nanofillers of Al and Fe in two varying particle sizes to be used as hot-melt adhesives for reversible bonding processes with the use of microwave technology. Reversible bonding relates to circular economy enhancement practices, like repair, refurbishment, replacement, or renovation. The physical–chemical, mechanical, and dielectric characteristics were considered to determine the impact of particle size and metal type. Through the investigation of electromagnetic radiation absorption in the composites, it was discovered that the optimal bonding technique could potentially involve a frequency of 915 MHz and a power level of 850 × 103 W/kg, resulting in an efficient process lasting 0.5 min. It was ultimately proven that the newly created hot-melt adhesive formulas can be entirely recycled and repurposed for similar bonding needs.

New Insights into Red and White Quinoa Protein Isolates: Nutritional, Functional, Thermal Properties

Quinoa (Chenopodium quinoa Willd.) seeds, renowned for their nutritional richness and balanced amino acid profile, offer promising potential as food ingredients. This study focused on extracting and characterizing the protein isolates from red and white quinoa varieties to evaluate their physicochemical and functional properties. Protein isolation involved alkaline solubilization and isoelectric precipitation, followed by characterization through amino acid analysis, phenolic profiling, scanning electron microscopy (SEM), zeta potential measurement, particle size distribution analysis, Differential Scanning Calorimetry (DSC), and rheological studies. The results showed that both the red and white quinoa protein isolates exhibited high protein content and essential amino acids, with notable differences in their amino acid compositions. The phenolic and flavonoid content varied between the red and white quinoa seeds, highlighting their potential antioxidant properties. SEM revealed distinct microstructural differences between the red and white quinoa protein isolates. Zeta potential measurements indicated the negative surface charges, influencing the stability in the solution. A particle size distribution analysis showed the monomodal distributions with minor variations in the mean particle size. The DSC profiles demonstrated multiple denaturation peaks, reflecting the complex protein compositions. Rheological studies indicated diverse gelation behaviors and mechanical properties. Overall, this comprehensive characterization underscores the potential of quinoa protein isolates as functional food ingredients with diverse applications in the food industry.

Electrospun Nanofiber Supported Nano/Mesoscale Covalent Organic Frameworks Boost Iodine Sorption.

Covalent Organic Frameworks (COFs) are benchmark materials for iodine sorption, but their use has largely been confined to crystalline bulk forms. In this state, COFs face diffusion limitations leading to slow sorption kinetics. To address this, a series of [2+3] imine-linked COFs with varying particle sizes and morphologies (mesospheres, nanoflowers, and bulk) is synthesized. Reducing particle size (from 826±48 to 412±22 nm) and adding surface protrusions in COF mesospheres improved iodine adsorption capacity (7.6 to 8.5 g g⁻¹), kinetics (K80%, 0.61 to 0.76 g g⁻¹ h⁻¹), and chemisorption efficiency. Notably, solvothermally synthesized (120°C, 5 d) crystalline bulk COF with accessible porous surfaces exhibited faster kinetics (K80%, 1.13 g g⁻¹ h⁻¹) than nano/mesoCOFs.This implies nano- and mesoCOFs exhibit surface aggregation that passivates their external binding sites and hinders iodine diffusion and mass transfer.To prevent this, morphologically controlled COF particles are immobilized onto electrospun polyacrylonitrile nanofibrous membranes via in situ growth strategy, creating a hierarchical structure that improved iodine diffusion pathways. This modification increased iodine sorption kinetics by 98%-153% and strengthened the charge-transfer process compared to COF powders.

Impact of PbZr0.5Ti0.5O3 Particle Size on the Ferroelectric and Magnetoelectric Properties of Mn0.5Zn0.5Fe2O4–PbZr0.5Ti0.5O3 Multiferroic Fluids

Herein, the impact of varying particle sizes of PbZr0.5Ti0.5O3 (PZT) powders on the ferroelectric and magnetoelectric properties of Mn0.5Zn0.5Fe2O4–PbZr0.5Ti0.5O3 multiferroic fluids is investigated. The PZT ferroelectric powders with different particle sizes (0.36, 0.28, 0.31, 0.75, 1.20 μm) are successfully prepared by altering the ball milling time. The multiferroic fluids demonstrate overall good sedimentation stability. The study finds that the dielectric constant first decreases and then increases with the reduction in particle size. The ferroelectric properties improve with the decrease in particle size and the application of a magnetic field. The multiferroic fluids with a particle size of 0.36 μm exhibit the highest polarization change (960.37%) under an electric field of 2000 Hz, 20 kV cm−1, and a magnetic field of 700 Oe. Furthermore, the magnetoelectric coupling coefficient first increases and then decreases with the reduction of the ferroelectric particle size. The multiferroic fluids with a particle size of 0.36 μm demonstrate the highest magnetoelectric coupling coefficient of 17.22 V cm−1 Oe−1 at 2000 Hz, indicating superior magnetoelectric coupling performance. These findings provide valuable insights into optimizing multiferroic fluids for applications requiring a high magnetoelectric coupling effect.

Stability of mass transfer parameters in critical regimes of two-phase flows

Stability of fractional separation parameters has been revealed in separation practice. Such stability is surprising, because an immense number of particles of various sizes take part in a process with a large number of random factors. Analysis of this phenomenon from the standpoint of statistical approach has explained its existence. A key notion of a statistical system is entropy. It is shown that a mass system evolves into a state corresponding to the maximal entropy value. Whenever fluctuations disturb the equilibrium of a system, its entropy decreases, and non-equilibrium processes return the system into its extreme state. This fact explains the stability of separation parameters.

Short-Term Impacts on Soil Biological Properties After Amendment with Biochar from Residual Forestry Biomass

The increasing challenges posed by climate change demand efficient strategies to mitigate soil degradation. Valorization of low-grade residual forestry biomass (acacia) into biochar could be used as a soil amendment strategy. A short-term incubation assay was conducted in forest soil, where the effects of biochar produced at two pyrolysis temperatures (450 °C and 550 °C) with varying particle sizes (S < 0.5 mm, M = [0.5; 3.15], L > 3.15 mm) and application rates (0, 3, 6 and 10% (w/w)) were assessed. Organic matter was analyzed through the water-soluble carbon, hot-water-extractable carbon, and microbial biomass. Microbial activity was evaluated by measuring the soil respiration and metabolic quotient. Biochar application increased the water-soluble carbon by 21 to 143% and the hot-water-extractable carbon by 27 to 137%, while decreasing the microbial biomass to 86%. The soil respiration and metabolic quotient increased in all the conditions, indicating an increase in microbial activity but low efficiency in carbon mineralization. This suggests the inefficient acclimatization of the microorganisms to biochar, lowering their ability to co-metabolize the recalcitrant carbon. Additionally, the potential adsorption of beneficial nutrients onto the biochar could have inhibited their release into the soil, hindering microbial growth. Increased biochar application rates resulted in adverse effects on microbial communities, indicating possible inhibitory effects on the soil biota.

Fabrication of a Random Laser by Embedding Copper Oxide Nanoparticles in Nonmetallic Host Media.

In this work, a simple, low-cost method for fabricating random gain media from Rhodamine B dye solution containing highly-pure CuO nanoparticles in transparent resin hosts is proposed. The spectroscopic characteristics of the dye solution samples were investigated with varying dye concentrations, along with nanoparticles of different particle sizes and concentrations. The fabricated samples were excited using two laser sources (405 and 530 nm) to record the fluorescence spectra. Our findings indicate that nanoparticles ranging in size from 15 to 78 nm may not have a significant impact on the fluorescence intensity or the peak wavelength at which maximum fluorescence occurs. Additionally, the fluorescence peak width, centered around 595 nm showed minimal sensitivity to the variation in particle size. The optimal concentration of nanoparticles in the dye solution was determined based on the optimum values of scattering spectral width and anisotropy parameter. Subsequently, the gain coefficient was calculated and correlated with these two parameters. It was found that the samples with the highest fluorescence intensity can be achieved using dye dissolved in transparent resin at a molar concentration of 5 × 10-5 M, containing 0.03-0.04 mg of CuO nanoparticles with a particle size of 78 nm.

Quantitative characterization of multiple cracks and permeability in coral sand engineered cementitious composites based on micro-computed tomography

Seawater–coral sand engineered cementitious composites (SCECCs) offer an effective solution for marine construction by utilizing local resources, thereby reducing costs and improving efficiency. This study examines the crack characteristics and permeability of SCECCs after loading, which are less understood aspects of these materials. Uniaxial tension tests were performed on SCECC specimens with varying particle sizes and aggregate types. High-resolution micro-computed tomography (micro-CT) and 3D visualization techniques were employed to analyze the formation and distribution of cracks as well as the permeability properties of the material. The findings indicate that as the maximum particle size increases, the volume fraction of cracks decreases. The crack distribution density initially rises and then falls with increasing particle size, while the spacing of cracks show the opposite trend. Specimens with 0.60mm aggregates demonstrated the most uniform and favorable crack distribution, outperforming similar freshwater–quartz sand ECC mixtures. Key factors influencing the permeability of cracked SCECCs include the pore throat parameters, volume ratios of pores and pore throats across different radii, and the spatial distribution of these structures. The SCECC’s ability to disperse deformation among numerous small cracks significantly enhances its impermeability, making it a highly suitable material for marine engineering applications.

Molecular dynamics mechanism of incorporating ZnO with varying particle sizes into ECTFE coatings and its impact on corrosion resistance

A composite coating of zinc oxide/chlorotrifluoroethylene copolymer (ZnO/ECTFE) was prepared on the surface of carbon steel via electrostatic spraying and heat treatment at 260 ℃. The influence of ZnO particle size variations on the anticorrosive properties of ECTFE coating was investigated by characterizing the microstructure, adhesion, hydrophilic/hydrophobic properties, electrochemical corrosion performance, as well as the dynamics simulation analysis on water molecule and chloride ions diffusion in the coating. The results show that the ECTFE coating incorporated with 100nm ZnO has the highest surface roughness (Roughness coefficient Ra = 30.6nm), the most robust adhesion (Bonding pull-out strength = 5.22MPa), and the lowest corrosion current density after a 90-day immersion (Icorr,90d = 4.05 × 10⁻⁸ A∙cm⁻²). These improvements represent an increase of 81.67% and 59.9% compared to the pure copolymer coating (Icorr,90d = 2.21 × 10⁻⁷ A∙cm⁻²) and the coating incorporated with 200nm ZnO (Icorr,90d = 1.01 × 10⁻⁷ A∙cm⁻²), respectively. This phenomenon can be attributed to the addition of small-sized ZnO, which enhances the density of the coating, induces a hydrophobic transition on its surface, strengthens the double electric layer effect, thereby improving its resistance against water molecule and chloride ions diffusion and ultimately enhances the corrosion resistance.

Air moisture harvesting in soil for indoor agriculture: A comparative study of moisture dynamics in shallow porous beds

Indoor farming can mitigate water scarcity, declining crop yields, and excessive chemical use in agriculture. However, it demands innovative solutions to reach its full potential. This paper presents a novel indoor plant cultivation technique that leverages atmospheric moisture. Shallow soil bed cooling from below can induce condensation within the soil pores, providing a sustainable water source for plant growth. We tested this method on wheat seed cultivation, observing a 40% growth increase in seedlings with cooled soil beds. We conducted a detailed study of moisture dynamics in porous sand beds to understand the underlying mechanisms of this technique. Choosing sand as a medium isolated the effects of porosity, temperature, and capillary action on moisture condensation. Sand's inertness allows a concentrated analysis of moisture dynamics without interference from chemical reactions or microbial activity. Experiments with cooled sand of varying particle sizes showed moisture condensation levels of 0.025, 0.042, and 0.092 kg/kg for coarse, fine, and superfine sand over 11 days. In soil, moisture reached 0.124 kg/kg over 22 days, highlighting the impact of porosity, temperature, and capillary forces. Our findings reveal exponential moisture increase over time and a linear relationship between bed water content and specific heat. The method is practical and adaptable, especially for remote locations and arid regions, as renewable energy sources can power it. This approach could revolutionize indoor agriculture, particularly in controlled environment systems. Controlling soil temperature can optimize growth conditions, increase yields, and minimize environmental impact. It offers versatility and scalability for various crops and systems.

A comparative study of thermal sprayed Al2O3-TiO2 coatings on PM AISI 316L

The widespread use of stainless steels (SS) in various applications is hindered by their inadequate wear resistance, hardness and high density. Structural metallic components fabricated via powder metallurgy (PM) exhibit lower densities compared to those produced by conventional methods due to their inherent high porosity. However, this compromises their mechanical and corrosion performance. This study has investigated the application of pure Al2O3 and Al2O3 + 13 %TiO2 powders with varying particle sizes on PM AISI 316L substrates to enhance their mechanical and wear properties. The phase composition, microhardness, coating morphology, surface roughness, porosity and wear rate of coated and uncoated samples were comparatively analysed to elucidate the influence of both TiO2 addition and coating powder particle size on the mechanical properties and surface morphology of the samples. Microstructural and XRD studies confirmed good mechanical and metallurgical bonding of the coatings to the substrate. All of the coated samples exhibited 24 to 34 times higher surface roughness and 1.3 to 2.1 times lower porosity values compared to the substrate. The finer sized TiO2 added alumina-based coating powder reduced the surface roughness and porosity value to 1.8 and 1.4 times respectively while the use of the coarser sized one reduced these values to 1.3 and 1.2 times respectively compared to the pure Al2O3 coated surface. 8-times higher hardness and 70-times lower wear rate values compared to the substrate were the most significant improvements observed in the pure Al2O3 coated surface among all coated samples. Although TiO2 addition to the coating powder decreased hardness by 1.1 times and increased wear rate by 1.8 times, spraying finer TiO2 added coating powders resulted in a slight improvement in both hardness and wear resistance compared to the coarser one.

Data-driven mechanical behavior modeling of granular biomass materials

Significant equipment downtime, mainly caused by the variable attributes and complex mechanical behavior of granular biomass materials, has challenged the great potential of biofuel generation. Expensive and time-consuming lab experiments are not affordable in fully characterizing material behavior for samples with all possible attributes. In this paper, we present data-driven modeling of the cyclic axial compression and ring-shear stress–strain behavior for granular biomass materials with different moisture contents and mean particle sizes. Laboratory characterization data of milled pine samples, with a mean particle size of 2, 4, and 6 mm and a moisture content of 0%, 20%, and 40%, were employed to train two machine learning (ML) models independently. The sequential model takes a sequence of loading history into Gated Recurrent Units (GRU) and predicts the next step of strain/stress with a feed-forward neural network. In contrast, the incremental model takes only the current state to predict the stiffness/compliance coefficient and compute the stress/strain increment. Both models account for material variations in particle sizes and moisture content. After training, both models demonstrate their high efficiency and accuracy in predicting the mechanical behavior of samples with a diverse set of unseen material properties, augmenting the existing laboratory data set. They also effectively capture the underlying physics, which involves increased compressibility as moisture content rises and a linear relationship between applied compression and shear strength. This effort established the foundation for comprehensive data-driven constitutive modeling tailored for unconventional granular materials.

Experimental investigation on heat and moisture transfer of propylene glycol-mixed steam in porous media

Propylene glycol (PG)-mixed steam enhanced extraction is a promising remediation technique for removing semi-volatile organic compounds (SVOCs) from the unsaturated zone. However, the mechanisms of heat and moisture transfer during PG-mixed steam injection remain unclear. In this study, a 2D experimental system was developed to enable non-invasive monitoring of the spatio-temporal distribution of temperature and degree of saturation during steam injection into porous media. Experiments were conducted to observe the migration of PG-mixed steam in horizontal and vertical planes across three varying particle sizes, while pure superheated steam injection experiments serving as a comparison. Temperature field results show that the addition of PG decreases the zone of influence during steam migration, while significantly enhancing the emergence of the superheated steam zone. The influence of particle size on the area variance of the saturated steam zone is greater than that of the superheated steam zone. The downward migration of the superheated steam front due to density different between PG vapor and air is impeded with decreasing permeability. Furthermore, saturation field results reveal that the condensed liquid within the superheated zone is a PG solution. The downward migration of condensates with high PG concentration might increase the potential risk of beneath groundwater pollution, highlighting the significance of understanding PG migration during PG-mixed steam injection.

Effect of Molybdenum Bisulfide (MoS2) Particle Size on Tribological and Vibration Reduction Properties of Thermoplastic Polyurethane

The incorporation of lubricating filler can improve the self-lubricating properties of polymers and mitigate friction-induced vibration under harsh conditions. However, filler performances significantly vary depending on its size. In this study, molybdenum bisulfide (MoS2) particles of various sizes were utilized as lubricating additives to reinforce thermoplastic polyurethane (TPU). The results showed that an appropriate decrease in the particle size of MoS2 facilitated more efficient stress transfer from the polymer to the particle due to strengthened interfacial interaction, resulting in improved mechanical properties of the reinforced TPU composites. Additionally, the adsorption property of the MoS2 particle improved, extending the duration of the MoS2 tribofilm. These beneficial phenomena endow TPU composites with excellent tribological and frictional vibration reduction properties, with the 500 nm MoS2 presenting the best reinforcing effect. However, further reduction in particle size caused particle agglomeration, which adversely affected the mechanical and self-lubricating properties of the composite and eventually reduced the frictional vibration reduction properties. The findings obtained herein provide a valuable reference for developing a novel polymer with excellent friction and vibration reduction properties.

Assessment of inter- and intra-granular fracture behaviors of polycrystalline LiNixCoyMn1-x-yO2 particles during a charging process

LiNixCoyMn1-x-yO2 (NCM) particles have been used as cathode materials for lithium-ion batteries because of their augmented energy density and elevated operational voltage. However, polycrystalline NCM (PC-NCM) particles exhibit intergranular, intragranular, or hybrid inter/intragranular fractures during electrochemical cycling. In this study, a chemical–mechanical coupling model, an embedded cohesive zone model damage unit, is developed to simulate the fracture evolution of randomly aggregated PC-NCM particles. A damage index is proposed to characterize crack evolution by including the comprehensive influence of crack number, length, and area. The influence of variations in fracture toughness, C-rates, and primary particle size on inter/intragranular fracture evolution is discussed in detail. The coexistent intergranular and intragranular fracture phenomena are successfully simulated and agree well with existing experimental observations. The simulation results indicate that local stress concentration leads to inter- and intra-granular fractures. Increasing the intragranular fracture toughness effectively prevents intragranular fractures but exacerbates intergranular fractures. Higher C-rates worsen intergranular fractures and increase the PC-NCM particle damage value. The effects of the primary particle size on particle damage vary with C-rate and fracture toughness ratio. This study enhances the understanding of the fracture mechanism of PC-NCM particles and offers valuable insights into their design.

Uptake, removal and trophic transfer of fluorescent polyethylene microplastics by freshwater model organisms: the impact of particle size and food availability

As an emerging contaminant, microplastics (MPs) are widely distributed in freshwater ecosystems and pose potential threats to aquatic organisms, attracting significant attention from both the scientific community and the general public. However, there is still uncertainty regarding the mechanisms of MPs transfer within aquatic biota and how particle size and food availability influence their transport patterns. In this study, zebrafish (Danio rerio) were selected as a model organism to investigate the uptake and elimination of fluorescent polyethylene (PE) MPs under different exposure scenarios (waterborne or trophic transfer, with or without food) and varying particle sizes (ranging from 10-300 μm at concentrations of 0.1, 2, and 300 mg/L). Additionally, water fleas (Daphnia magna) were provided as prey for the fish. The dynamic accumulation of PE-MPs sized between 10-20 μm at a concentration of 25 mg/L by daphnia was also determined along with its impact on animal feeding behavior. The results demonstrated that both organisms were capable of ingesting PE-MPs during exposures lasting up to 24 hours for daphnia and up to 72 hours for zebrafish. Furthermore, rapid elimination rates were observed within just 30 minutes for daphnia and between 6-12 hours for zebrafish. The presence of food reduced MPs uptake and removal by daphnia but significantly increased MP elimination by fish. Zebrafish showed a preference for ingesting larger-sized MPs that they could easily recognize; however, trophic transfer from daphnia to fish was found to be the primary route of ingestion specifically for PE-MPs sized between 10-20 μm. The findings suggest that while fish directly ingest fewer invisible MPs from the water column, they still accumulate these particles through predation on contaminated prey organisms. Therefore, it is imperative to prioritize the ecological risks associated with the transfer of MPs from zooplankton to fish.

Effect of Particle Size on Raman Signal Strength of Silicate Minerals

ABSTRACTUnderstanding the effects of particle size is necessary for quantifying minerals in mixtures using Raman spectroscopy. Raman signal intensity is evaluated using six common silicate minerals (two olivines, two pyroxenes, and two feldspars) at 10 particle size ranges. For olivines and feldspars, the highest peak intensities are observed in samples with 38–63 and 63–106 μm particle sizes. There is no such consistent trend for the pyroxene samples, although the overall low signal strength complicates those measurements. Raman spectra of samples with varying particle sizes appear to be influenced by two competing effects: scattering from particle boundaries and effective sampling volume.