Composite Particles Research Articles

Single‐Particle Electrochemical Cycling Single‐Crystal and Polycrystalline NMC Particles

AbstractLi(Ni,Mn,Co)O2 (NMC) is one of the most widely used cathode materials for lithium‐ion batteries. Most commercial cathodes utilize polycrystalline particle morphologies, which have a characteristic “meatball” shape. Recently, there has been interest in replacing polycrystalline particles with single‐crystal particles, which are believed to have improved cycle life due to the absence of intergranular cracking. However, the effects of single‐crystal particles on rate capability show conflicting results. In this work, single‐particle electrochemistry using a microelectrode array to test the kinetics of 40 polycrystalline (3–12 µm) and 13 single‐crystal (2–4 µm) NMC cathode particles is conducted. The results show that single‐crystal particles have much higher reaction overpotentials than polycrystalline ones. Moreover, larger single‐crystal particles show higher overpotentials than smaller ones, while the polycrystalline particles display no size effects despite the greater variability. These findings are attributed to intergranular cracking and the penetration of the liquid electrolyte, which enables much faster reaction kinetics. In characterizing the electrochemistry of individual particles, the results confirm that these single‐crystal particles would have much poorer rate kinetics and more challenges with fast charge and discharge compared to polycrystalline particles of the same composition.

Curcumin loaded high internal phase emulsions: Formulation and potential to alleviate DSS-induced ulcerative colitis

Ulcerative colitis (UC) is a chronic, incurable disease that causes great suffering to patients. High internal phase emulsions (HIPEs) are promising carriers of curcumin (Cur), which has a beneficial effect on UC. The retention rate of Cur encapsulated in HIPEs prepared by pea protein isolated nanoparticles/octenyl succinic anhydride-modified linear dextrin composite particles (PPINs/OSA-LD) or PPINs reached 84.85% and 85.98%, respectively, which was significantly higher than that of Cur dissolved in corn oil (73.84%) due to the superior protection of the emulsion interfacial structure. The HIPEs showed higher bioaccessibility of Cur (31.16%) due to the higher degree of free fatty acid release. After emulsion treatment, the symptoms of UC were ameliorated, mainly manifested by the recovery of body weight, growth of the colon, down-regulation of pro-inflammatory factors, up-regulation of anti-inflammatory factors, and balance of gut microbiota composition. The Cur-loaded HIPEs show an outstanding improvement in UC.

Mechanical behavior of Al /AL2O3p-SiCp hybrid composite fabricated by hot pressing method

Hybrid particulate metal matrix composites with specific strength can be used in various applications. The mechanical properties of these composites can be improved by correctly choosing the type, volume fraction, size, and distribution of reinforcements and metal matrix. In this research, to make Al/Al2O3-SiC hybrid composites, aluminum chips were prepared by machining, and then the chips were coated with Al2O3 and SiC reinforcements by suspension method. For composite making, first, aluminum-coated chips were molded inside a steel mold and after heat treatment at 645 °C for 2 h the chips were hot pressed. The microstructure of the fabricated composites was examined by optical and SEM microscope, and then compression and tensile strength behavior were studied. The microstructural results showed a sound composite without any porosities and cracks. The hybrid composite with 12 wt% reinforcements showed high compressive strength (370 MPa).

Effect of Muddy Water Characteristics on Infiltration Laws and Stratum Compactum Soil Particle Composition under Film Hole Irrigation

Effect of Muddy Water Characteristics on Infiltration Laws and Stratum Compactum Soil Particle Composition under Film Hole Irrigation

Mechanisms of slow-release antibacterial properties in chitosan‑titanium dioxide stabilized perilla essential oil Pickering emulsions: Focusing on oil-water interfacial behaviors

Perilla essential oil (PLEO) offers benefits for food preservation and healthcare, yet its instability restricts its applications. In this study, chitosan (CS) and TiO2 used to prepare composite particles. TiO2, after being modified with sodium laurate (SL), was successfully introduced at 0.1 %–3 % into the CS matrix. The resulting CS-SL-TiO2 composite particles can be formed by intertwining and rearranging through intramolecular and intermolecular interactions, and form an O/W interface with stability and viscoelasticity. The Pickering emulsions stabilized by these particles exhibit non-Newtonian pseudoplastic behavior, shear-thinning properties, and slow-release characteristics, along with antibacterial activity. Emulsions with 0.5 % and 1 % CS-SL-TiO2 composites demonstrated superior antibacterial effects against Escherichia coli and Staphylococcus aureus. The study revealed that all emulsions undergo Fickian diffusion and a sustained release of PLEO, with the Ritger-Peppas model best describing this release mechanism. The slow-release behaviors positively correlates with interfacial pressure, composite particle size, composite particle potential, composite contact angle, emulsion particle size and emulsion potential, but negatively correlates with diffusion rate, penetration rate, release kinetics and release rate. The findings lay groundwork for developing slow-release antimicrobial emulsions within polysaccharide matrices, showcasing promise for antimicrobial packaging solutions and enhanced food preservation techniques.

A natural protein-lipid co-assembly as efficient Pickering emulsifier from egg yolk sphere microgel prepared via high-pressure homogenization

Egg yolk sphere is a kind of natural colloidal histological structure formed by the co-assembly of a large number of proteins and lipids, which has the dual functions of hydrophilic and lipophilic for application in emulsion. In this study, egg yolk sphere microgels (EYSMs) were prepared by high pressure homogenization (HPH) technique at various pressures (0–90 MPa) and used as Pickering emulsifiers for emulsification to obtain oil-in-water emulsions with an oil-water ratio of 11:9. The microscopic morphology, structure, and physicochemical properties of EYSMs were analyzed. The results showed that EYSMs obtained at 60 MPa (60-EYSMs) exhibited superior emulsifying properties with an emulsifying activity index (EAI) of 2.8 m2/g and an emulsifying stability index (ESI) of 356.6 min, resulting in enhanced storage stability of the emulsion for 30 d. The HPH treatment decreased the lipid content in EYSMs while creating a more homogeneous protein-lipid arrangement, which provided EYSMs with balanced hydrophilic and hydrophobic sites to improve emulsifying properties. Furthermore, the free sulfhydryl groups and hydrophobic moieties exposed by HPH promoted -S-S- formation on the EYSMs surface, promoting the increase in surface hydrophobicity and emulsifying ability. The confocal laser scanning microscopy (CLSM) and cryogenic scanning electron microscopy (cryo-SEM) revealed that the EYSMs adsorbed at oil-water interface and formed an intercross-linked spatial three-dimensional network structure, which worked as a physical barrier to the stable emulsion formation. This study introduces a novel research concept and delves into the emulsification mechanism of protein-lipid composite particles, offering a fresh insight for the development and utilization of emulsifiers.

Ultrasonic assisted adsorption of methylene blue using blood clam shell as a low-cost adsorbent

Methylene blue is a synthetic dye used in various industries, such as wood, linen, and silk. Generally, as much as 10–200 mg/L of methylene blue is released into the environment and potentially polluting the environment. One of methylene blue removal method from wastewater is adsorption, particularly using blood clam (Anadara granosa) shells adsorbent. Blood clam shells contain CaCO3 (up to 98.7 %) that can be utilized to adsorb methylene. Furthermore, methylene blue adsorption can be enhanced by employed the ultrasonic wave. This research aims to prepare, characterize, and employ blood clam shells as a low-cost adsorbent in the ultrasonic-assisted methylene blue adsorption. The parameters studied were the adsorbent preparation method, adsorbate pH, adsorbent mass, contact time, and initial concentration. The adsorbent preparation method affected the morphology, elemental composition, functional groups, and average particle size, which were confirmed using SEM-EDX, FTIR, and PSA, where this kind of investigation has never been conducted before. Optimum conditions for methylene blue adsorption were obtained for adsorbent A3, pH 12, adsorbent mass of 0.5 g, contact time of 60 min, and initial concentration of 10 ppm, with a removal percentage of 98.614 %. This removal percentage increased by 63.119 % (espescially in A3) compared to without ultrasonic waves, which could only remove methylene blue by 35.495 %. Ultrasonic-assisted adsorption of methylene blue using blood clam shells adsorbent proceeded according to the Sips isotherm model (R2 = 0.9953) and pseudo-second-order kinetics (R2 = 0.939). A3 shows an extraordinary performance, with reusability up to six cylces. The adsorption occurs by electrostatic interaction between adsorbent's surface and cations in methylene blue, chemisorption, and the formation of monolayer adsorbate in heterogenous A3's surface.

(Invited) Photocatalytic H2 Evolution Activity of Anisotropic-Shaped ZnSe-AgInSe2 Solid Solution Quantum Dots with a Near-IR-Responsivity

Semiconductor nanocrystals, often referred to as quantum dots (QDs), exhibit unique physicochemical properties due to the quantum size effect when their size is less than 10 nm. In our previous works, we successfully synthesized Zn-Ag-In-S (ZAIS) solid solution QDs with a tunable energy gap (Eg) and then reported the photocatalytic activity for H2 evolution depending on their morphology and particle composition [1,2]. However, ZAIS QDs have limited light absorption with wavelengths less than ca. 600 nm, restricting their utilization of near-infrared light in solar light. In this study, we report the preparation of near-IR-responsive QD photocatalysts with use of Zn-Ag-In-Se (ZAISe) solid solution semiconductors. Precise controls over their morphology and particle composition enabled to vary their photocatalytic H2 evolution activity.ZAISe QDs with different compositions and particle shapes (sphere or rod) were synthesized by thermal decomposition of corresponding metal acetates and selenourea in a mixture solution of oleylamine and dodecane thiol at 250 oC. The chemical composition of QDs was controlled by varying the Zn fraction in metal precursors, ensuring nearly stoichiometric composition.The obtained QDs with a rod shape had lengths varying from ca. 10 to 100 nm, correlating with an increase in the Zn fraction. The onset wavelengths of absorption spectra of the ZAISe QDs were red-shifted from 500 nm to 900 nm with decreasing Zn fraction, indicating that the Eg of ZAISe QDs was controlled between visible and near-infrared wavelength regions.The QDs modified with dodecane thiol showed poor dispersibility in water and almost no photocatalytic activity for H2 evolution. In contrast, the surface modification of QDs with 3-mercaptopropionic acid enabled to uniformly disperse in an aqueous solution. The photocatalytic activity of ZAISe QDs was investigated for H2 evolution as a model reaction. The irradiation to ZAISe QDs in an aqueous solution containing Na2S and Na2SO3 as hole scavengers was carried out using Xe lamp light (λ> 350 nm). The H2 evolution rate exhibited a remarkable dependence on both the composition and particle shape of ZAISe QDs. The photocatalytic activity showed a tendency to increase with the enlargement of the Eg of QDs, probably due to the negative shift of conduction band minimum potential. The optimum H2 evolution activity was obtained with rod-shaped QDs having the Eg of 1.65 eV, being twice as large as that of spherical QDs with a similar Eg. This behavior can be attributed to the change of the crystal facets exposed on the QD surface. References Kameyama, T. Takahashi, T. Machida, Y. Kamiya, T. Yamamoto, S. Kuwabata, and T. Torimoto, J. Phys. Chem. C, 2015, 119, 24740-24749.Torimoto, Y. Kamiya, T. Kameyama, H. Nishi, T. Uematsu, S. Kuwabata, and T. Shibayama, ACS Appl. Mater. Interfaces 2016 , 8, 27151-27161.

Solution-Phase Synthesis and Composition-Dependent Optical Properties of Less-Toxic Multinary Ag–Mn–Sn–S Quantum Dots

Introduction Multinary quantum dots (QDs) have been promising materials as an efficient light absorber in solar light energy conversion systems. These QDs including Cu(In,Ga)(S,Se)2 and Cu2ZnSn(S,Se)4 QDs, consisting of less-toxic elements, are known for their high absorption coefficient and excellent processability. However, the cation disorder in Cu2ZnSn(S,Se)4 has been observed to cause a bandgap fluctuation and an emergence of additional antisite defects1. An effective approach to mitigating such disorder involves the substitution of Cu or Zn with larger cations. Here we focus on Ag2MnSnS4 (AMTS) due to similar optical properties with Cu2ZnSn(S,Se)4 QDs. The energy gap of bulk AMTS was reported to ca. 2.0 eV2, making it suitable for efficient solar light energy conversion systems. However, creating AMTS structures can be challenging, often requiring high temperatures or pressures. Thus, a simpler synthesis route for preparing QDs will offer a new perspective in addressing this issue, and the size reduction will enable to tune their optical bandgap. In this study, we report for the first time the solution-phase preparation of AMTS QDs. The resulting QDs exhibited composition-dependent optical properties depending on the Ag/metal ratio. Experimental The synthesis of AMTS QDs was conducted by a facile colloidal heating-up method. Precursors of corresponding metal complexes and sulfur powder were dispersed in a mixture solvent of 1-dodecanethiol (DDT) and oleylamine (OLAm), followed by the heat treatment at more than 423 K. Thus-obtained solution was subjected to centrifugation to remove large precipitates, and target QDs were isolated from the supernatant by adding methanol and ethanol as a non-solvent, followed by centrifugation. Results and Discussion AMTS QDs with diameters less than 6 nm were obtained. The absorption spectra of AMTS QDs varied with the Ag/metal ratio. The onset wavelength was blue-shifted from ca. 670 nm to ca. 500 nm with a decrease in the Ag fraction. In the case of Ag/metal= 0.50, that is, the stoichiometric Ag2MnSnS4, the bandgap was determined to 2.0 eV, being similar to the bulk bandgap of monoclinic Ag2MnSnS4 2. The optical bandgap was monotonously increased from 2.0 eV to 2.4 eV as the Ag/metal ratio decreased from 0.50 to 0.05.The electronic energy structure of AMTS QDs was determined from the ionization energy of the QDs, which was evaluated from the onset energy of the photoelectron yield spectra in air. The conduction band minimum level shifted from –3.5 eV to –3.1 eV with a decrease in the Ag fraction, while the valence band maximum was constant at ca. –5.5 eV. The crystal structure and particle morphology were almost unchanged even when the particle composition was varied, indicating that the change in bandgap resulted from the composition. The stability of QDs was improved by surface coating with a ZnS shell. Subsequent ligand exchange with a hydrophilic molecule enabled the uniform dispersion of QDs in an aqueous solution without changing their optical properties and chemical composition. These findings open up possibilities for utilizing ATMS QDs in various applications such as photocatalysis and bioimaging in aqueous media. Reference 1 J. Kumar, and S. Ingole, J. Alloys Compd., 865, 158113 (2021). 2 Frank N. Keutsch, Dan Topa, Rie Takagi Fredrickson, E. Makovicky, and W.H. Paar, Mineral. Mag. 83(2), 233–238 (2019).

Total Holographic Characterization of Large Particle Contaminants in Chemical Mechanical Polishing (CMP) Slurries

Nanoparticle slurries are widely used in semiconductor CMP processing. Accurately evaluating quality attributes of CMP slurries can be challenging for standard optical methods. Ceria slurries can be too optically dense and inhomogeneous for most optical measurements. Diluting the slurry can induce agglomeration or break up the agglomerates already present in the slurry. Previous studies of silica CMP slurries demonstrated that Total Holographic Characterization (THC) is effective for monitoring agglomeration in slurries. THC uses particle holograms to determine particle size and composition. Ceria nanoparticles have higher refractive indexes than silica nanoparticles, and produce more scattered light, which can reduce the signal of measurements of agglomerates, making accurate, reproducible measurements more challenging. Ceria slurry was successfully analyzed at concentrations typically used in semiconductor processing. Effective-medium theory is used to understand the variation in refractive index of large particle contaminants as compared to native slurry nanoparticles and other contaminants such as pad debris.

Synthesis of Plasmonic Copper/Copper Oxide Nanostructures as (Photo)Catalysts

Plasmonic nanostructures can enhance the photocatalytic efficiency of semiconductors under visible light irradiation. While the plasmonic-enhanced photocatalysis has been widely studied, rigorous efforts focus on designing novel noble metal nanostructures by altering particle size, shape, and composition to optimize their interaction with light to influence the catalytic properties. However, the need for a more cost-effective material as an alternative for noble metals has led us toward the exploration of copper and their oxides for photocatalysis. In this work, we synthesize different morphologies of copper nanostructures (i.e., 10 nm and 50 nm nanoparticles, as well as nanowires. Copper nanostructures are prone to be oxidized over time; however, the degree of oxidation varies with the size and shape of the nanostructure, thereby creating hybrid copper/copper oxide nanostructures with unique optical and (photo)catalytic properties. The hybrid nanostructures are characterized by X-ray powder diffraction and transmission electron microscopy. Their optical properties are studied by UV-vis spectroscopy along with simulation. We then further study the use of these hybrid nanostructures as (photo)catalysts for redox reactions – the reduction of 4-nitrophenol (4-NP) and the oxidation of tetramethylbenzidine (TMB). The (photo)catalytic properties will be correlated with the size, shape, and the degree of oxidation of these hybrid nanostructures. The mechanisms of both reactions on the hybrid copper/copper oxide (photo)catalysts will be discussed.

Achieving High Performance with High Oxygen Permeability Ionomer (HOPI) in Heavy Duty Fuel Cell MEAs

Heavy-duty PEM fuel cells are expected to last 25,000-30,000 hours in the field. Therefore, materials, components, and interfaces used in these systems must be highly resistant to severe mechanical and chemical stress. Novel, highly active stable Pt and ordered PtCo intermetallic nanoparticles with well-controlled particle size and composition have been synthesized on a highly efficient PGM-free single metal active site rich carbon, to maximize their synergistic effects for enhanced performance and durability. Integrating these catalysts integrated with high O2 permeability ionomer (HOPI) in membrane electrode assemblies (MEAs) improved their fuel cell performance and durability, allowing the MEAs to achieve >1.2 A/cm2 at 0.7 V after 150k square wave accelerated stress test (AST) cycles, with a performance loss < 40 mV after 150K AST cycles.In a PEM fuel cell, the catalyst ink formulation and mixing processes control catalyst layer coating quality, electrode morphology, and the resulting fuel cell performance and durability. Catalyst ink properties are a result of complex solvent-catalyst-ionomer interactions that depend on the mixing method employed. Here, we compare the performance and durability of electrodes made from ball milled inks for Mayer rod coating before and after the catalyst scale up. Ink rheology and catalyst particle size are used to correlate ink properties to electrode morphology and structure and ensure consistency from batch to batch, and from small lab scale to subsequent scale-up. We evaluate and discuss the challenges that arise when coating the more viscous inks on decals, where the HOPI creates many bubbles in the ink. We also present the challenges of hot-pressing inks that contain HOPI, and how employing a Nafion overspray made with different solvents (isopropanol vs. ethanol) can improve hot-pressing. We investigate the how ionomer to carbon ratio affects hot pressing with HOPI and crack formation in the electrode via scanning electron microscopy (SEM).This work provides a comprehensive understanding of interactions between Pt, PtCo, carbon, ionomer, membrane, and GDLs and their impact on electrode structure, fuel cell performance and durability, as well as considerations for scale up to a R2R fabrication process. The attained information will be used to improve fuel cell electrode design, fabrication and scale-up.Acknowledgement: The project is financially supported by the Department of Energy’s Fuel Cell Technology Office under the Grant DE-FOA-0002360 (Phase I) and DE-SC0021671 (Phase II). Figure 1

A versatile sample-delivery system for X-ray photoelectron spectroscopy of in-flight aerosols and free nanoparticles at MAX IV Laboratory.

Aerosol science is of utmost importance for both climate and public health research, and in recent years X-ray techniques have proven effective tools for aerosol-particle characterization. To date, such methods have often involved the study of particles collected onto a substrate, but a high photon flux may cause radiation damage to such deposited particles and volatile components can potentially react with the surrounding environment after sampling. These and many other factors make studies on collected aerosol particles challenging. Therefore, a new aerosol sample-delivery system dedicated to X-ray photoelectron spectroscopy studies of aerosol particles and gas molecules in-flight has been developed at the MAX IV Laboratory. The aerosol particles are brought from atmospheric pressure to vacuum in a continuous flow, ensuring that the sample is constantly renewed, thus avoiding radiation damage, and allowing measurements on the true unsupported aerosol. At the same time, available gas molecules can be used for energy calibration and to study gas-particle partitioning. The design features of the aerosol sample-delivery system and important information on the operation procedures are described in detail here. Furthermore, to demonstrate the experimental range of the aerosol sample-delivery system, results from aerosol particles of different shape, size and composition are presented, including inorganic atmospheric aerosols, secondary organic aerosols and engineered nanoparticles.

Non-equilibrium excited-state fractionally quantized Hall effects observed via current bias spectroscopy

Studies of fractional quantum Hall effects (FQHE) across various two-dimensional electronic systems (2DES) have helped to establish the equilibrium FQHE many-body ground states with fractionally charged excitations and composite particles in condensed matter. Then, the question arises whether an FQHE system driven to non-equilibrium can approach a different stationary state from the known equilibrium FQHE states. To investigate this question, we examine FQHE over filling factors, ν, 2 ≥ ν ≥ 1 under non-equilibrium finite bias conditions realized with a supplementary dc-current bias, IDC, in high mobility GaAs/AlGaAs devices. Here, we show that all observable canonical equilibrium FQHE resistance minima at ∣IDC∣ = 0 undergo bimodal splitting vs. IDC, yielding branch-pairs and diamond shapes in color plots of the diagonal resistance, as canonical FQHE are replaced, with increasing IDC, by excited-state fractionally quantized Hall effects at branch intersections. A tunneling model serves to interpret the results.

Modeling aerosol transmission spectra from n(λ) and k(λ) infrared optical constants measurements of organic liquids and solids

The effects of light scattering and refraction play significantly different roles for aerosols than for bulk materials, making it challenging to identify aerosolized chemicals using traditional spectral methods or spectral reference libraries. Due to a potentially infinite number of particle morphologies, sizes, and compositions, constructing a database of laboratory-measured aerosol spectra is not a practical solution. Here, as an alternative approach, the measured n/k optical vectors of two example organic materials (diethyl phthalate and D-mannitol) are used in combination with particle absorption / scattering theory (Mie theory and FDTD) and the Beer-Lambert law to generate a series of synthetic infrared transmission / scattered light spectra. The synthetic spectra show significant differences versus simple slab transmission spectra, even for small changes in particle size (e.g., 5 vs. 10 µm) for both single particles and ensembles, potentially serving as useful reference data for aerosol sensing. For spherical single particles with diameters of 1 to 10 µm, FDTD simulations predict changes in the magnitudes of spectral shifts and the shapes of the peaks vs. particle size with only small deviations from Mie theory predictions, yet reliably capture the direction of the shifts. Typical spectral peak shifts in the longwave infrared correspond to Δλ ∼0.20 µm (∼34 cm-1) when compared to corresponding slab transmission spectra. Additionally, synthetic spectra generated from the n/k values derived using two different methods (KBr pellet transmission and single-angle reflectance) are compared using the Mie theory model.

Construction of micro-nano structured Si/C anode armed with rGO hollow spheres for high-performance lithium-ion hybrid capacitors

Because of the unique ability to combine high energy density with high power density, lithium-ion hybrid capacitors (LICs) have generated significant interest. Among the various anodes being explored for LICs, silicon (Si) stands out as a particularly promising anode material due to its high theoretical capacity. Nevertheless, the formidable challenge lies in the rapid capacity fade resulting from substantial volume expansion. Herein, a simple and efficient spray drying technique was used to fabricate a Si@rGO@NC composite with micro-nano structure. In this composite, Si nanoparticles are encapsulated between reduced graphene oxides (rGO) hollow spheres and a layer of carbon is coated on the surface of both the Si and the micron-sized composite particles, forming a rigid and mechanically stable structure. The composite combines the high activity of nano-Si with the industrially easy handling of micron-scale particles. Moreover, the rGO hollow spheres not only enhance the electrical conductivity but also buffer the volume expansion of the electrode and provide channels for the rapid transport of electrolyte/ions. Thanks to its advantageous structural features, the constructed LICs with activated carbon as cathode can achieve a Max. energy/power density of 253.1 Wh kg−1/10,824.1 W kg−1 and maintain 84.3 % of its initial capacitance after 8000 cycles. The micro-nano structured design concept of Si-based materials developed in our work could offer new insights and directions for the future development of Si-based energy storage devices.

Selective capture of PM2.5 by urban trees: The role of leaf wax composition and physiological traits in air quality enhancement

Human health risks from particles with a diameter of less than 2.5 µm (PM2.5) highlight the role of urban trees as bio-filters in air pollution control. However, whether the size and composition of particles captured by various tree species differ or not remain unclear. This study investigates how leaf attributes affect the capture of PM2.5, which can penetrate deep into the lungs and pose significant health risks. Using a self-developed particulate matter (PM) resuspension chamber and single-particle aerosol mass spectrometer, we measured the size distribution and mass spectra of particles captured by ten tree species. Notably, Cinnamomum camphora (L.) J.Presl and Osmanthus fragrans Lour. are more effective at capturing particles under 1 µm, which are most harmful because they can reach the alveoli, whereas Ginkgo biloba L. and Platanus × acerifolia (Aiton) Willd. tend to capture larger particles, up to 1.6 µm, which are prone to being trapped in the upper respiratory tract. Leaf physiological traits such as stomatal conductance and water potential significantly enhance the capture of larger particles. The Adaptive Resonance Theory neural network (ART-2a) algorithm classified a large number of single particles to determine their composition. Results indicate distinct inter-species variations in chemical composition of particles captured by leaves. Moreover, we identified how specific leaf wax compositions—beyond the known sticky nature of hydrophobic waxes—contribute to particle adhesion, particularly highlighting the roles of fatty acids and alkanes in adhering particles rich in organic carbon and heavy metals, respectively. This research advances our understanding by linking leaf physiological and wax characteristics to the selective capture of PM2.5, providing actionable insights for urban forestry management. The detailed exploration of particle size and composition, tied to specific tree species, enriches the current literature by quantifying how and why different species contribute variably to air quality improvement. This adds a crucial layer of specificity to the general knowledge that trees serve as bio-filters, offering a refined strategy for planting urban trees based on their particulate capture profiles.

Study on carbon allotrope abrasive particles based on C60 molecule for diamond chemical mechanical polishing

In this study, we developed C60 reactive diamond composite particles for the chemical mechanical polishing (CMP) of diamond substrates by applying the high hardness and high reactivity of the C60 molecule. When diamond substrates were polished using these C60 diamond composite particles, the polished surface was found to be superior to that of diamond particles. In addition, when the composite particles were irradiated with ultraviolet light to produce polishing fine particles, the polishing rate was improved by about 30%. These results indicate that the composite nanoparticles that reacted with C60 have the potential to remove even the hardest of diamond substrates.

Effect of different precipitants on the formation of ultrafine 3 mol% yttrium-stabilized zirconia nanopowders by reverse precipitation

This study proposes a simple method for preparing highly dispersed ultrafine 3 mol% yttrium-stabilized zirconia nanopowders (3YSZ NPs), which provide high-quality powders for use in high-performance ceramics. First, 3YSZ NPs were prepared using a reverse precipitation method with different precipitants: NaOH, NH3·H2O and (NH3)2CO3. The thermal decomposition, phase evolution, morphology and chemical composition of the precursor particles and 3YSZ NPs were analysed. The effects of precipitant and reaction conditions on 3YSZ NPs were systematically studied. The results show that there are differences in the mechanism of powder synthesis using the co-precipitation method among the three precipitants. In addition, ultrafine 3YSZ NPs with minimum agglomeration and high sphericity can be prepared using NaOH. Y3+ and ZrO2+ cannot coprecipitate in solution according to the designed molar ratio in the NH3·H2O and (NH4)2CO3 methods. Considering agglomeration, crystallinity and elemental distribution, NaOH is the best precipitant. The prepared zirconia powder exhibits high crystallinity, good dispersion, a narrow particle size distribution and a tetragonal phase structure. By investigating the effects of calcination temperature, titration end point pH and NaOH concentration, 3YSZ NPs with an average particle size of 22.29–38.94 nm are obtained.

Innovative composite fluidized hydrogel GAC particles for effective membrane fouling mitigation and membrane integrity protection

Membrane filtration is recognized as an environmentally friendly and cost-efficient technology for water treatment, but membrane fouling is still a significant challenge that increases maintenance costs and reduces membrane lifespan. Particle scouring can effectively mitigate fouling with lower energy consumption. This study investigates the use of fluidized granular activated carbon (GAC) particles encapsulated with hydrogel layers to enhance fouling mitigation in microfiltration systems treating surface water. The proposed hydrogel-modified GAC particles aim to balance scouring efficiency with membrane integrity. The results demonstrate that optimizing hydrogel preparation conditions significantly enhanced the mechanical strength and surface hydrophilicity of GAC particles. The incorporation of hydrogel layers notably improved membrane fouling mitigation, reducing transmembrane pressure (TMP) by 19.3 %, 27.1 %, and 34.3 % for layer thicknesses of 0.5 mm, 1.0 mm, and 1.5 mm, respectively. The hydrodynamic behavior of fluidized GAC particles was significantly improved, enhancing the effectiveness of fouling mitigation in water treatment processes. Additionally, the hydrogel layer effectively protected membrane integrity and inhibited carbon release, ensuring minimal damage and stable permeability. This study underscores the pivotal role of hydrogel layers in improving the performance and longevity of membrane filtration systems, when fluidized GAC particles are used for membrane fouling control.