Shell Particles Research Articles

Yolk-shell FeS@N-doped carbon nanosphere as superior anode materials for sodium-ion batteries

Iron sulfides have shown great potential as anode materials for sodium-ion batteries (SIBs) because of their high sodium storage capacity and low cost. Nevertheless, iron sulfides generally exhibit unsatisfied electrochemical performance induced by sluggish electron/ion transfer and severe pulverization upon the sodiation/desodiation process. Herein, we constructed a yolk-shell FeS@NC nanosphere with an N-doped carbon shell and FeS particle core via a simple hydrothermal method, followed by in-situ polymerization and vulcanization. The FeS particles intimately coupled with N-doped carbon can accelerate the electron transfer, avoid severe volume expansion, and maintain structural stability upon repeated sodiation/desodiation process. Furthermore, the small particle size of FeS can shorten ion-diffusion distance and facilitate ion transportation. Therefore, the FeS@NC nanosphere shows excellent cycling performance and superior rate capability that it can deliver a high capacity of 520.1 mAh g−1 over 800 cycles at 2.0 A g−1 and a remarkable capacity of 625.9 mAh g−1 at 10.0 A g−1.

Calcium Alginate Core–Shell Liquid Beads Encapsulated with Microalgae for Wastewater Treatment

Liquid beads are core–shell particles with a liquid core and a solid shell. Calcium alginate liquid beads have been emerging as a promising platform for cell encapsulation. These beads have demonstrated their capability of encapsulating and culturing a wide range of human cells for tissue engineering. However, a significant research gap remains in the application of alginate liquid beads for encapsulating photosynthetic microorganisms. Herein, fast‐growing microalgae strain Chlorella vulgaris is encapsulated into calcium alginate liquid beads to facilitate the removal of nutrients from wastewater, minimizing the risk of eutrophication. Liquid bead‐microalgae systems are prepared, using different calcium ion concentrations as crosslinking ions. It has been thoroughly characterized for their morphologies, cell growth patterns, nutrient removal capabilities, and overall stability throughout the wastewater treatment process, with upflow anaerobic sludge blanket effluent as the wastewater model. The results indicate that the liquid bead‐microalgae system with the highest calcium ion concentration (5%) performs more efficiently, exhibiting a well‐formed crosslinking structure, leading to rapid cell growth with the highest cell density and the most effective removal of nutrients. The findings from this study provide valuable insights for future optimization and upscaling efforts in wastewater treatment systems based on calcium alginate liquid beads.

Development of a rapid HPLC-fluorescence method for monitoring warfarin metabolites formation: In vitro studies for evaluating the effect of piperine on warfarin metabolism and plasma coagulation

Warfarin, a widely prescribed anticoagulant, is highly effective for various coagulation disorders. However, its efficacy is limited by a narrow therapeutic index and frequent drug interactions, especially those involving metabolism by Cytochrome P450 (CYP450) enzymes. Piperine, found in black and long pepper, possesses blood-thinning properties and has been observed to inhibit CYP3A and CYP2C enzymes linked to warfarin metabolism. This study investigated the effect of piperine on warfarin metabolism in liver microsomes using a rapid and sensitive HPLC-Fluorescence method. The use of PFP (pentafluorophenyl) column with core shell particles provided the selectivity and resolution to resolve warfarin and its 4-, 6-, 7-, and 10-hydroxy metabolites in addition to the internal standard naproxen in less than 3 min. This is the fastest analytical assay for warfarin and its major metabolites reported to date, making it ideal for metabolic studies. The applicability of the method was demonstrated by monitoring the metabolism of S-warfarin in human and rat liver microsomes, and evaluating the inhibitory effect of piperine on metabolite formation. The results showed that piperine inhibited the formation of the major metabolite, 7-hydroxywarfarin, with half-maximal inhibitory concentration (IC50) 14.2 μM and 3.2 μM in human and rat liver microsomes, respectively. Furthermore, coagulation studies in vitro using rat plasma showed that piperine does not affect prothrombin time (PT) and activated partial thromboplastin time (aPTT). This study suggested that piperine may present a potential drug interaction with warfarin at the metabolism level, but has no direct effect on the activation of the extrinsic or intrinsic coagulation cascades. Further clinical investigation is therefore required, as piperine may increase the bioavailability of warfarin, thus increasing risk of serious adverse events in patients.

Fabrication of stable monolayer liquid marbles with reduced particle coverage and locomotion on hydrophilic surface

Liquid marbles are non-wetting, particle-covered microdroplets with a core-shell structure that are used in sample transport, material synthesis, and real-time sensing. Optimizing the distribution of shell particles remains a challenge, due to a tendency for aggregation via spontaneous assembly, which often leads to multilayered structures. Here, we outline a simple method for fabricating water-filled, monolayer liquid marbles with adjustable particle coverage rates, greatly reducing particle consumption. The soft liquid marbles are enclosed by a small quantity of modified polystyrene microspheres and display good atmospheric stability. The rolling behavior of flexible liquid marbles with wide coverage rates is then characterized. Contrary to common perception, the marbles with transparent openings exhibit high maneuverability on hydrophilic surfaces, and also excel in fusion, reaction and surface cleaning, with an elongated operational duration and a wide visualization range. The study provides new insights into the implementation of liquid marble-based miniaturized platforms.

The construction of iron-based catalysts encapsulated by graphite for CO2 hydrogenation to light olefins

Developing efficient catalytic materials and unveiling the active factors are significant for selective hydrogenation of CO2 to light olefins (C2–4=). Herein, Fe3O4-FeCx nanoparticles coated by graphite without other doped elements were synthesized successfully. The optimal catalyst exhibited CO2 conversion of 48.0%, C2–4= space–time yield of 29.0 mmol·g−1·h−1, and a stability of 100 h (3.0 MPa, 320 °C, and GHSV = 12000 mL·g−1·h−1). The core–shell structure derived from the strong interaction between the phenolic hydroxyl group of resin and iron ions, as well as the encapsulation of the copolymer P123. The characterization results revealed that the size of core–shell particles and thickness of graphite layers could be regulated by P123, which affected the conversion of CO2 and products distribution significantly. Moreover, the combined results of quasi in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs) and Raman spectra suggested small particle size and thin graphite shell strengthen the adsorption and conversion of CO2, playing an important role in the formation of light olefins. This work proposes a simple and feasible synthesis strategy to construct Fe3O4-FeCx particles encapsulated by graphite shell, which provides insights into catalysts design and the reaction mechanism of CO2 conversion to light olefins.

Microfluidic Synthesis and Properties of Thermoresponsive Hydrogel Core–Shell Particles

An approach is demonstrated for the generation of swellable core–shell particles in the sub-millimeter range using a one-step microfluidic method. Particles are made of an agarose gel core and a shell consisting of hydrogel based on crosslinked poly-(N-isopropylacrylamide) (PNIPAM). Solidification of the core was achieved by cooling below the sol–gel temperature, while the shell was cured by photoinitiated co-polymerization. The shell of the particles is reversibly thermoresponsive; it contracts upon heating, releasing water, and becomes hydrophobic. The transition temperature as well as the stability of the particles are mainly affected by the shell monomer composition, while they are less affected by the type of the core material. Such composite particles remain swellable after drying.

Mechanical and tribological behaviour of three-dimensional printed almond shell particles reinforced polylactic acid bio-composites

Recently, composite filament development for three-dimensional printing has emerged and is used for numerous applications. The present research work develops neat polylactic acid and Almond Shell Particles reinforced polylactic acid bio-composites for three-dimensional printing and investigates the effects of printing orientation, including 0°, 45° and 90° orientation, on the tribological and mechanical behaviours of three-dimensional printed materials. The novel almond shell particles reinforced polylactic acid filaments are extruded by the filament extrusion method with the presence of 10% almond shell particles in the polylactic acid matrix, and the samples are three-dimensional printed by the fused filament fabrication technique. Mechanical characteristics such as tensile, flexural, compressive strength, and shore hardness are evaluated with respect to various three-dimensional printing orientations. The surface quality of the three-dimensional printed polylactic acid composite samples is analysed with respect to length and diameter deviation. Length accuracy of the 90° oriented polylactic acid and almond shell particles reinforced polylactic acid bio-composite samples exploits a better accuracy of 99.12% and 98.81%, respectively. It is shown that adding almond shell particles to the polylactic acid matrix decreases the flexural and tensile strength. Among the printing orientations, 0° flat samples result in the maximum tensile strength of 36 and 28 MPa for the neat polylactic acid and almond shell particles reinforced polylactic acid composites, respectively. The lowest contact angle of 54° is observed on the almond shell particles reinforced polylactic acid bio-composites three-dimensional printed with a 90° orientation. The highest contact angle value of 94° is observed on the neat polylactic acid three-dimensional printed with a 0° printing orientation. A tribological study is carried out under dry conditions on the pin-on-disc tribometer by varying the sliding speed (1, 2, and 3 m/s) and load (10, 20, and 30 N). The result shows that the lowest coefficient of friction of 0.22 is achieved for the almond shell particles reinforced polylactic acid bio-composite samples with a 0° printing orientation under a sliding load of 10 N. These kinds of newly developed compostable materials can be used for developing disposable orthotic foot appliances.

Design and Synthesis of Polystyrene-Occluded Reactive Core–Shell Particles of Natural Rubber to Balance Stiffness and Toughness in Poly(lactic acid)

Design and Synthesis of Polystyrene-Occluded Reactive Core–Shell Particles of Natural Rubber to Balance Stiffness and Toughness in Poly(lactic acid)

Recycled Household Plastic and Oil Palm Filler Reinforced Epoxy Composite for Lightweight Construction Applications

Polypropylene is extensively used in aerospace, automotive and construction applications due to its versatile properties. This project aims to reduce plastic and oil palm waste and promote the development of strong, sustainable and eco-friendly construction materials. The objective of this project is to develop a sustainable yet high-performance construction material by incorporating polypropylene particles, oil palm empty fruit bunch (OPEFB) fibres and oil palm shell (OPS) particles into epoxy composites through the hand lay-up method. The composite specimens undergo ASTM D638 tensile test to determine the tensile properties. The addition of PP particles in varying weights shows decrease in tensile strength, likely due to poor dispersion and compatibility with the epoxy matrix. Incorporating 3 wt% OPEFB fibres with fibre length from 2mm to 4mm improves tensile strength by 2.32% and 23.36% respectively at higher PP particle loadings which are 15 wt% and 25 wt%. Adding 1 wt% and 3 wt% OPS particles improves the tensile strength by 2.96% and 4.68% respectively, in composites with 10 wt% PP particles and 3 wt% OPEFB fibres. The tensile performance may be improved by treating PP particles with compatibilizers such as silane or maleic anhydride grafted polypropylene.

Structural Color Materials with Color Mixing Effect Using Noble Metal‐Free Plasmonic Particles in SiO2–ZrN System

AbstractStructurally colored materials with a color mixing effect are developed using SiO2–ZrN core–shell particles, where ZrN nanoparticles used as shells exhibited localized surface plasmon resonances (LSPRs). ZrN nanoparticles (10–30 nm) are attached to monodispersed SiO2 particles by modifying SiO2 particles with polymers. The attached ZrN nanoparticles exhibited a plasmon resonance absorption band at 700 nm. These SiO2–ZrN core–shell particles have a highly monodisperse particle size and assemble into a particle‐stacked film with Bragg diffraction light in the visible spectrum. The particle‐stacked film of the SiO2–ZrN core–shell particles exhibited the maximum reflection depending on the particle size of the SiO2 core. The ratio of the reflection intensity in the long‐wavelength region corresponding to the ZrN absorption to that in the short‐wavelength region of the particle‐stacked film containing the ZrN shell is less than that of the ratio in only SiO2 particle‐stacked film. The results reveal that these particle‐stacked films exhibit a “color mixing effect” that combines specific wavelength absorption through plasmon resonance and specific wavelength diffraction owing to the periodic structure without using precious metals.

The preparation and feasibility analysis of magnetic orientation method in the study of thermal insulation composite materials in the field of electronic packaging

AbstractAs an emerging field of current technological development, the heat dissipation performance of electronic packaging materials has become the key to determining product reliability. Therefore, the applied thermal interface materials (TIMs) need to simultaneously meet the performance indicators of thermal conductivity, mechanics, and insulation. Although BN had excellent in‐plane thermal conductivity and insulation performance, it is currently difficult to achieve vertical orientation of powder which leads the layered powder cannot complete a continuous and effective heat transfer path along the Z‐axis direction inside the composite material. In order to solve the above two problems, out‐of‐plane thermal conductive composite was prepared by introducing magnetic oriented method. In order to comprehensively evaluate the thermal conductivity, mechanical and electrical properties, BN@Fe3O4/EP magnetic oriented composites were compared with BN@PDA‐Al2O3/EP composite prepared by mechanical blending method. The vertical thermal conductivity of the magnetic oriented composite material was 2.24 W/(m·K) at 30 vol%, which was 3.39 times that of the blended composite material and 12.4 times that of pure EP. This proves that the magnetic oriented composite materials prepared by the research institute can meet the vertical heat transfer needs in the field of electronic packaging and have high research value in this area.Highlights BN@Fe3O4 core–shell particles were prepared with both thermal conductivity and magnetic controllability. The thermosetting composites were prepared by heated through preliminary gel point and then cured at high temperature. The orientation of powder inside the matrix was constructed, resulted in excellent out‐of‐plane heat transfer performance. Comparisons were made between various properties of magnetic oriented materials and conventional blend materials. The magnetic orientation method is feasible in the field of electronic packaging.

Platinum/Tantalum Carbide Core–Shell Nanoparticles with Sub‐Monolayer Shells for Methanol and Oxygen Electrocatalysis

AbstractCore–shell architectures provide great opportunities to improve catalytic activity, but achieving nanoparticle stability under electrochemical cycling remains challenging. Herein, core–shell nanoparticles comprising atomically thin Pt shells over earth‐abundant TaC cores are synthesized and used as highly durable electrocatalysts for the methanol oxidation reaction (MOR) and the oxygen reduction reaction (ORR) needed to drive direct methanol fuel cells (DMFCs). Characterization data show that a thin oxidic passivation layer protects the TaC core from undergoing dissolution in the fuel cell‐relevant potential range, enabling the use of partially covered Pt/TaC core–shell nanoparticles for MOR and ORR with high stability and enhanced catalytic performance. Specifically, at the anode the surface‐oxidized TaC further enhances MOR activity compared to conventional Pt nanoparticles. At the cathode, the Pt/TaC catalyst feature increases tolerance to methanol crossover. These results show unique synergistic advantages of the core–shell particles and open opportunities to tailor catalytic properties for electrocatalytic reactions.

Exploring the potential of pulverized oyster shell as a limestone substitute in limestone calcined clay cement (LC3) and its implications for performance

With the advent of rapid climate change and global warming, the cement industry has been actively striving to minimize its carbon footprint. An effective approach for reducing carbon emissions is to utilize supplementary cementitious materials (SCMs). Limestone calcined clay cement (LC3) has garnered significant attention because of its ability to reduce clinker use by approximately 45 wt%, compared to ordinary Portland cement. However, the raw materials involved in LC3 production, which are obtained through mining and heating of raw clay, also counts toward the carbon footprint. Therefore, the present study aims to explore the feasibility of using oyster shells as a replacement for limestone in LC3 systems. Various amorphousness of calcined clay were tested to investigate the hydration reaction and strength of the oyster shell calcined clay cement (OC3). Data collected using techniques such as X-ray diffraction, thermogravimetry, scanning electron microscopy, isothermal calorimetry, compressive strength testing, and 29Si nuclear magnetic resonance spectroscopy were analyzed to elucidate the hydration reaction mechanisms of OC3, considering the type of calcite (oyster shell or limestone) and the extent of the transformation of kaolinite clay to metakaolin. The findings of this study demonstrate that oyster shells can effectively replace limestone as a raw material for LC3. Furthermore, the irregular morphology of the shell particles enhanced the hydration reaction and development of the cement’s microstructure.

One-step synthesis of Ag@polyaniline core–shell particles for efficient removal of radioactive iodine

One-step synthesis of Ag@polyaniline core–shell particles for efficient removal of radioactive iodine

DEVELOPMENT OF COMPOSITE MATERIALS FOR TRICYCLE BRAKE PADS

Coconut fiber and rice dust are locally sourced, developed, and evaluated as agro-waste materials to replace carcinogenic asbestos fibers in brake pad production. The process involves crushing, grinding, and sieving coconut fiber into a powder, mixing it with steel dust, carbon black, and epoxy resin, filling a mould, adding hardener, and pressing and curing samples at 250 °C. The produce is tested for mechanical properties, with optimal brake pad properties achieved using a 100μm sieve grade, enhancing interfacial bonding between resin and coconut shell particles. The hardness, compressive strength, ash content, specific gravity, wear rate, and water absorption values were found to be 258, 113 N/mm2, 40%, 1.91, 3.23 mg/m, and 0.63%. The study found that coconut shell has qualities similar to those needed for brake pad material and asbestos replacement in brake pad production. Coconut shell, with its 100μm particle size, has the potential to replace asbestos-based brake pad manufacturing, reducing harmful components and environmental impact.

Preparation of core–shell silica particles with tunable pore size by phenylethanol as swelling agent for chromatographic separation

The core–shell particles with tunable pore size were synthesized by a bi-phase reaction successfully. By adjusting the amount of phenylethanol, fibrous shells with tunable pore sizes ranging from 4 to 19 nm could be obtained in one pot. The obtained silica microspheres were used for chromatographic separation after modification with octyltrichlorosilane and end-capping with N-(trimethoxysilylpropyl)imidazole. Better resolutions of nitroimidazoles and anilines were obtained on the end-capped stationary phase. This particle could serve as an HPLC stationary phase with good reproducibility and particular selectivity.

Silicon eccentric shell nanoparticles fabricated by template-assisted deposition for Mie magnetic resonances enhanced light confinement

We report a structure of silicon eccentric shell particles array, fabricated by the SiO2 particles monolayer array assisted deposition of amorphous Si, for high-efficiency light confinement. The SiO2 particles monolayer array is tailored to regulate its interparticle distance, followed by silicon film deposition to obtain silicon eccentric shell arrays with positive and negative off-center distance e. We studied the Mie resonances of silicon solid sphere, concentric shell, eccentric shell and observed that the eccentric shell with positive off-center e supports superior light confinement because of the enhanced Mie magnetic resonances. Spectroscopic measurements and finite difference time domain simulations were conducted to examine the optical performance of the eccentric shell particles array. Results show that the Mie magnetic resonance wavelength can be easily regulated by the size of the inner void of the silicon shell to realize tunable enhanced light confinement. It was found silicon shell with D = 460/520 nm offered high enhanced light absorption efficiency at wavelength of λ = 830 nm, almost beyond the bandgap of the amorphous silicon.

Skin Temperature-Triggered Switchable Adhesive Coatings for Wearing Comfortable Epidermal Electronics

Smart adhesives with switchable adhesion strength on demand are crucial for ensuring the stability of the epidermal electronics-skin interface and preventing skin damage caused by device detachment. However, challenges such as harsh triggering conditions, lack of precise control over material comprehensive performance, and difficulty in achieving micron-level controlled integration of materials on device surfaces hinder the application of switchable adhesives in epidermal electronics. Herein, we designed a coatable, thermally-triggered switchable adhesive that has a high adhesion of 68.8 N/m at skin temperature, e.g., 33 °C, and after a slight cooling, e.g., 20 °C, the adhesion decreases to 6.59 N/m, resulting in a high switching ratio of 10.4. The switching time is < 1 min. This unique property is achieved by combining side-chain crystalline polymers and self-adhesive polymers through a strategy of constructing core–shell particles. The results of thermal analyses, rheology, and solid-state nuclear magnetic resonance indicate that a rapid and reversible crystallization-melting transition within the material is the essence of the adhesion switching. By depositing the material on flexible electrodes using spraying technology, we have obtained an ultra-thin (<5 μm), and peelable on-demand epidermal electrode, demonstrating the advantages of emulsion materials in the fabrication of wearing comfortable devices.

Deformation and rupture of Janus nanoparticle-stabilized Pickering emulsion in confined channel

The interaction between Pickering emulsions and confined channels is vital for their industrial applications. However, how solid particle shells modulate the deformation stability and rupture limit of Pickering emulsions in contact with wall remains poorly understood. In this work, mechanical deformation and rupture of Janus nanoparticles (JNP)-stabilized Pickering emulsions on solid surfaces are elaborated by molecular dynamics (MD) simulations. A universal master-type predictive model is developed for the first time to describe the contact behavior of Pickering emulsions against surfaces with distinct wettability. The contact stress of an emulsion is determined by the equivalent elastic modulus of the emulsion, geometric deformation function, and the influence of the JNP shell and its interactions. Moreover, hydrophobic surfaces lead to the rupture of Pickering emulsions in compression. The rupture can be delayed by increasing JNP surface coverage (ϕ). Especially, once ϕ reaches a critical value, the JNP shell can form an ordered quasi-solid structure, significantly enhancing the emulsion stability. These results can aid in the design or screening of specific Pickering emulsions to manage their deformation and rupture on the solid surface, in applications ranging from water treatment and drug delivery to environmental remediation and mobility control in oil recovery.

Granular Skeleton Optimisation and the Influence of the Cement Paste Content in Bio-Based Oyster Shell Mortar with 100% Aggregate Replacement

The purpose of this paper is to propose a methodology to optimise the granular skeleton assembly of cementitious materials containing non-spherical aggregates. The method is general and can be applied to any granular skeleton whatever the aggregate shape, size, or composition because it is simply based on the direct minimisation of the intergranular porosity to consequently increase the skeleton’s compactness. Based on an experimental design approach, this method was applied to and validated for bio-based oyster shell (OS) mortar with 100% aggregate replacement. First, the best combination of seven crushed oyster shell particle classes was determined and compared with a standardised sand skeleton (0/4 mm) and three other non-optimised OS gradings in terms of intergranular porosity. In particular, it is shown that simply mimicking a reference grading curve initially designed for spherical particles with non-spherical particles led to poor performances. Then, different mortars were cast with the standardised sand skeleton, the optimised OS grading, and the three other non-optimised OS gradings by keeping the water-to-cement ratio (0.5), the aggregate bulk volume, and the cement paste content constant. Mechanical tests in compression confirmed the higher performance of the optimised OS mortar, validating the global optimisation approach. However, the high elongation of the oyster shell aggregates led to high skeleton intergranular porosities—even after optimisation—and the cement paste content needed to be adapted. For a given granular skeleton and for a constant aggregate bulk volume, the increase of the cement paste content led to an increase of both the filling ratio and the mechanical properties (compressive and flexural strengths). Finally, it is shown that the proposed skeleton optimisation and a cement paste content adjustment allowed recovering good mechanical properties for an oyster shell mortar with 100% aggregate replacement, especially in flexural tension.