Spherical Particles Research Articles

One-step spray solution combustion synthesis of nanostructured spherical Ca3Co4O9: The fuel effect

In the research, a one-step method for the rapid preparation of spherical nanostructured particles of Ca3Co4O9, involving the combustion of reactive aerosol drops containing calcium and cobalt nitrates as the metal precursors and hexamethylenetetramine as the fuel, is reported. The results of thermodynamic analysis and study of crystalline structure of obtained materials suggest that the reaction in the investigated system proceeds with heat release, which indicates its self-sustaining nature. Applying hexamethylenetetramine fuel at φ range of 0.4 – 0.6 and ambient temperature of 900 ℃ resulted in formation of Ca3Co4O9 powders with narrow particle size distribution of 0.2 – 1 µm. Microstructural studies revealed that the Ca3Co4O9 particles are hollow with nanometer-scale wall thicknesses and their surface consists of lamellar grains with sizes ranging from 14 to 100 nm.

Phase Preparation of Xiao-chai-hu Decoction and its Pharmacodynamics of Acute Liver Injury.

Self-emulsifying nano-phase of traditional Chinese medicine are a research hotspot. Xiao-Chai-Hu decoction is a commonly used compound decoction in clinical practice, which is of great research significance. The aim of this study was to isolate and characterize the self-emulsifying nano-phase and other phases of Xiao-Chai-Hu decoction, and to study the effects of each phase on acute liver injury. The liquid medicine was prepared employing centrifugation followed by dialysis. Single- factor investigation methodology was utilized to optimize the preparation parameters for both phases. Characterization of the formulated phase involved analyses such as surface morphology assessment, measurement of nanoparticle size and Zeta potential using an analyzer, observation of the Tyndall effect, conducting diffusion and dilution tests, examination under a microscope, and structural visualization via transmission electron microscopy (TEM). Furthermore, an acute liver injury model was established in rats through intraperitoneal injection of D-Galactosamine (D-Gal- N). To assess hepatic function and oxidative stress status, serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), superoxide dismutase (SOD) activity, and malondialdehyde (MDA) content in liver tissue were quantified. The liver coefficients for each group were calculated as an additional parameter. For histopathological evaluation, liver tissue sections from the experimental group were stained with Hematoxylin and Eosin (H&E) and examined microscopically under light conditions. These revisions aim to enhance clarity, correct minor grammatical errors (such as capitalization of "HE" to "H&E"), and ensure a smoother flow of information without altering the scientific content of your original text. Successful establishment and separation of four distinct phases were achieved, including the self-emulsifying nano-phase, precipitation phase, suspension phase, and true solution phase. The self-emulsifying nano-phase was characterized as spherical particles with an average diameter of approximately 100 nm. Pharmacodynamic assessments revealed that both Xiao-Chai-Hu decoction and its self-emulsifying nano-phase significantly reduced liver coefficients and alanine aminotransferase (ALT) levels compared to controls (P<0.05). However, no statistically significant differences were observed in regards to aspartate aminotransferase (AST) concentrations, malondialdehyde (MDA) content, or superoxide dismutase (SOD) activity between the treatment groups and control (P>0.05). These findings indicate that both Xiao-Chai-Hu decoction and its self-emulsifying nano-formulation ameliorated D-GalN-induced acute liver injury, albeit without statistically distinguishable efficacy between them (P>0.05). The presence of a self-emulsifying nano-phase within Xiao-Chai-Hu decoction is confirmed, and this nano-phase emerges as a therapeutically efficacious component in mitigating acute liver injury.

Cinnamon Particle‐Stabilized Gas Marbles: A Novel Approach for Enhanced Stability and Versatile Applications

AbstractSuspension of solid particles at interfaces is a common phenomenon, pivotal in natural, and industrial contexts. This study focuses on gas marbles which are single soap‐like air bubbles in air environment stabilized by colloidal particles. A unique stabilization method employing edible cinnamon particles is introduced. Unlike previous studies using spherical particles, the irregularly‐shaped micrometer‐sized cinnamon particles demonstrate remarkable long‐term stability through jamming and interlocking at the air‐liquid interface. Comprehensive characterization via optical and scanning electron microscopy, and contact angle experiments, elucidates the stabilization mechanism. These gas marbles exhibit exceptional resilience against drying, heating, freezing, and mechanical stress. They can be fabricated with various edible liquids offering extensive customization possibilities. This breakthrough introduces a promising method for creating stable gas marbles with edible particles, offering versatility for various fields and applications. The application scope includes surface catalysis and shock/vibration sensors, and also molecular gastronomy.

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.

Synthesis of boron-based High-Energy composite microspheres via the Co-Flow microchannel method

Boron-based metastable intermolecular composites (MIC), renowned for their swift energy release and elevated thermal output, exhibit significant promise for utilization in domains such as gunpowder, propellants, and powdered fuel ramjet fuels. The work successfully accomplished the safe and efficient preparation of B/Bi2O3 microunits by utilizing co-flow microchannel technology. The choice of the optimal binder, F2603, for this system was determined by simulation analysis. The practicality of the microchannel platform was then verified using Fluent. SEM analysis demonstrated that an amount of 10 % F2603 resulted in the formation of spherical particles. In terms of physical properties, boron treated with 10 % F2603 exhibits a reduction in its angle of repose from 35° of the raw material to 15°, along with a significant enhancement in hydrophobicity. Furthermore, the MICs lower the reaction temperature of raw boron from 840℃ to 770℃. In the constant volume combustion test, the MIC output pressure increased by 33.3 %. In the constant pressure combustion test, the MIC ignition delay time was reduced from 0.7262 s to 0.5566 s. The structural characteristics of the system decrease the distance for mass and heat transmission across components, resulting in improved overall performance. The study unequivocally demonstrates the efficacy of co-flow microchannel technology in swiftly, effectively, and securely producing energetic molecules. It establishes a solid foundation for future industrial manufacturing.

Motion and Orientation of Janus Spherical Particles at a Liquid-Air Interface Governed by the Moses Effect.

We investigated the motion of spherical polystyrene/polypyrrole-coated polystyrene Janus particles placed at an air/saline interface and driven by a permanent magnetic field of ca. 0.5 T. For the sake of comparison, the motion of pure floating polystyrene particles was studied. Both kinds of the studied particles moved toward the magnet and stopped at the boundary of the near-surface well produced by the magnetic field. The Moses effect-driven motion of floating Janus particles was analyzed and investigated under different strengths of the magnetic field and salt concentrations. The study of the Janus particle displacement led to the development of a unified theoretical framework explaining the mechanism of the motion. This framework predicts that the motion of particles placed at an air-salt solution interface is not only dictated by magnetic energy but also intricately influenced by the interplay of factors, including the curvature of the interface caused by the static magnetic field, gravitational potential, and capillary forces. The orientation of the particles was observed. A qualitative explanation of the observed phenomena is suggested. The investigated process has potential for the self-assembly of particles placed at the liquid/air interface.

Antifungal properties and molecular docking of ZnO NPs mediated using medicinal plant extracts

Significant postharvest losses and food safety issues persist in many developing nations, primarily due to fungal activities, including mycotoxin production. In this study, green synthesised zinc oxide nanoparticles (ZnO-NPs) were prepared from leaf extracts of Syzygium cordatum (ZnO 1), Lippia javanica (ZnO 2), Bidens pilosa (ZnO 3), and Ximenia caffra (ZnO 4). Physicochemical characteristics of the ZnO-NPs were determined using X-ray diffraction (XRD), Fourier transmission Infrared spectroscopy and ultraviolet–visible (UV–vis) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The XRD analysis confirmed the presence of a wurtzite crystal structure in the hexagonal shape of the ZnO nanoparticles (NPs), with an average size ranging between 25 and 43 nm. The microscopic examination of the morphology revealed the presence of spherical particles with sizes ranging from 37 to 47 nm in diameter. The antifungal efficacy of the ZnO-NPs was assessed against pathogenic plant fungi, including Botrytis sp. (STEU 7866), Penicillium sp. (STEU 7865), and Pilidiella granati (STEU 7864), using the poisoned food technique. Further antifungal evaluation of the ZnOPs was performed using the broth microdilution assay. A significant interaction between the type of ZnO-NPs and fungal species was observed, with the highest susceptibility in Mucor sp. to ZnO 2, achieving over 50% inhibition. Penicillium sp. also showed high susceptibility to all ZnO-NPs. Molecular docking results confirmed the strong H-bonding interactions of ZnO-NPs with fungal receptors in Mucor sp. and Penicillium sp., Botrytis sp. and P. granati exhibited the least susceptibility. Further tests revealed that ZnO 2 exhibited the highest inhibitory effect on Botrytis sp., with a low minimum inhibitory concentration (MIC) of 25 µg/mL, attributed to its larger positive zeta potential. This study indicates that ZnO NPs, particularly those mediated using Lippia javanica (ZnO 2), have promising potential as effective antifungal agents, which could play a significant role in reducing postharvest decay and losses.

Discerning computational, in vitro and in vivo investigations of self-assembling empagliflozin polymeric micelles in type-2 diabetes.

Empagliflozin (EMPA) is an SGLT2 inhibitor, a new class of anti-diabetic medication, indicated for treating type-2 diabetes. Its low permeability, poor solubility and bioavailability limits its use in management of diabetes. The study was aimed to formulate EMPA loaded polymeric micelles (PMs) to overcome these obstacles in oral absorption. In silico studies-molecular docking, molecular dynamic simulation (MDS), and quantum chemical calculation were employed to study the interaction of EMPA with different polymers. EMPA loaded TPGS polymeric micelles (EMPA-TPGS-PMs) were formulated by direct dissolution method and characterized in terms of surface morphology, entrapment, particle size, in vitro drug release, and in vitro cytotoxicity (HEK293 cells). In vivo pharmacokinetic and pharmacodynamic studies were also performed. The results suggested a good interaction between TPGS and EMPA with lowest binding energy compared to other polymers. Further MDS results and DFT calculations validated the stable binding of the complex hence TPGS was selected for further wet lab experiments. The EMPA-TPGS complex displayed lower value of Total energy (T.E.) than its individual components, indicating the overall stability of the complex while, the energy band gap (∆E) value lied between the two individual molecules, signifying the better electron transfer between HOMO and LUMO of the complex. Based on the solubility, entrapment and cytotoxicity studies, 5% TPGS was selected for formulating drug loaded micelles. EMPA-TPGS5-PMs presented a size of 9.008 ± 1.25nm, Polydispersity index (PDI) of 0.254 ± 0.100, a controlled release behaviour upto 24h. SEM and AFM images of the nanoformulation suggested spherical particles whereas, DSC, and PXRD studies confirmed the loss of crystallinity of EMPA. A 3.12-folds higher AUC and a greater reduction in blood glucose levels was exhibited by EMPA-TPGS5-PMs in comparison to EMPA-SUSP in mice model. EMPA-TPGS-PMs has exhibited better bio absorption and therapeutic effectiveness in diabetes treatment. This improved performance would open the possibility of dose reduction, reduced dosing frequency & dose-related side effects, improving pharmaco-economics and thereby improved overall compliance to the patient. However, this translation from bench to bedside would necessitate studies in higher animals and human volunteers.

Tailoring Co‐Free LiNi0.5Mn1.5O4 Material for High‐Voltage Lithium‐Ion Batteries: Particle Design &amp; Grain Boundary Engineering

AbstractCobalt‐free LiNi0.5Mn1.5O4 (LNMO) is a promising cathode material for high‐energy and power‐density lithium‐ion batteries (LIBs). However, its commercial adoption is hindered by rapid capacity degradation due to the unstable LNMO/electrolyte interface caused by LNMO's high operating voltage. Structural degradation from Jahn–Teller distortion and metal‐ion dissolution also contributes to poor cycling stability. Additionally, producing industrial‐grade LNMO with high tap density, low surface area and reduced metal‐ion dissolution is challenging. This study addresses these challenges through a rational material design approach, synthesizing LNMO with large spherical secondary particles (&gt;14.0 µm) and high tap density (&gt;2.0 g cm−3). The primary particles (1.5–6.0 µm) exhibit a truncated‐octahedral shaped morphology that predominantly exposes (111) surface facets, with fewer (100) surfaces, stabilizing the LNMO/electrolyte interface, reducing metal dissolution, and enhancing lithium‐ion kinetics. Silicon infusion into grain boundaries further improves structural integrity by forming a silicon‐rich phase. The tailored LNMO demonstrates exceptional rate capability, cycling stability, and improved interfacial kinetics, significantly advancing the potential for cobalt‐free LNMO in high‐voltage LIBs. This work highlights the importance of tailored cathode material design for achieving the performance and stability required for emerging high‐voltage LIBs applications.

Structure and plastic deformation of metastable Ag–Cu metal-matrix composites produced by a bottom-up way from Cu@Ag core–shell powders

AbstractTo understand mechanical behavior of metastable metal-matrix composites, Cu@Ag core–shell powders of two compositions, 51:49 and 80:20 (Cu:Ag in wt%), were compacted by spark plasma sintering. The microstructures of these metastable metal-matrix composites are characterized by single spherical particulates of pure Cu in the matrix of pure Ag in the former case while by aggregates of Cu particulates in Ag matrix in the latter one. The plastic deformation showed enhancement of the ultimate tensile strength compared to both pure component metals by a factor of ca. 3. It is shown that a part of plastic deformation can be correlated by a logarithmic dependence but a possibility to apply a polynomial (quadratic) correlation is suggested. As expected, the shape of the particulate changes during plastic deformation and depends on the level and type of the plastic deformation. A model is proposed showing that this dependence is of a hyperbolic character.

Development of cantharidin/baicalin co-delivery system based on mitochondrial targeting strategy for enhanced hepatocellular carcinoma therapy

Cantharidin (CTD) as a treatment for primary liver cancer are well known, and although structural alteration and nano-delivery are efficient in diminishing toxicity, its urinary and digestive toxicity has hindered its clinical application. Based on the synergistic effect of CTD and baicalin (BA) on proliferation inhibition of liver tumor cells, the highly expressed folic acid (FA) receptor of liver cancer cell membrane and the high negative membrane potential of tumor cell mitochondria, we synthesized CHEMS-FRFK and prepared a dual-ligand modified co-delivery liposomes (FA/FRFK-CTD/BA-Lips). Liposomes were spherical particles with uniform particle size, high encapsulation rate, good stability and no hemolysis. The results confirmed that FA/FRFK-CTD/BA-Lips had good targeting to mitochondria of tumor cells, and its target effect on mitochondria of HepG2 was better than that of Huh-7 cells. Compared with CTD, the cytotoxicity of liposomes on HepG2 is 7.0 times higher, while the cytotoxic effect on normal liver cells Thle-2 is 2.1 times lower. It may be related to increasing clathrin-mediated endocytosis, inhibiting tumor cell migration, arresting cell cycle in G1/G0 phase, and promoting mitochondria-mediated endogenous Bcl-2/Caspase 3 apoptosis pathway. Meanwhile, FA/FRFK-CTD/BA-Lips could alter the pharmacokinetic behavior of CTD and BA by increasing concentrations in vivo, slowing release and excretion, good anti-tumor with no obvious toxicity, and successfully delivered CTD/BA to liver tissue, tumor cells and mitochondria. Therefore, FA/FRFK-CTD/BA-Lips, as a delivery system targeting the mitochondria of liver cancer cells, has promising development potential, and could provide a new strategy for solving the problem of CTD toxicity and the treatment of hepatocellular carcinoma.

Synergistically enhanced electromagnetic absorption in barium ferrite/hollow carbon spheres/epoxy composites

The ongoing technological advancements have emphasized the importance of absorbent coatings, which are essential for effectively absorbing electromagnetic waves across various industries, including electronics, healthcare, and security systems. In this research, barium ferrite particles and hollow spherical carbon particles have been synthesized to investigate the synergistic effect of different compounds in absorbing electromagnetic waves in the epoxy coating. The barium ferrite particles were synthesized in two distinctive rod and spherical morphologies at 600 and 900 ºC, employing the sol-gel technique. Also, hollow spherical carbon particles were synthesized. Synthesized particles were analyzed structurally and chemically with an X-ray Powder Diffraction, Fourier infrared spectrometer, vibrating‐sample magnetometer, field emission Scanning Electron, and Raman spectroscopy.The absorption characteristics of a coating that contains rod and spherical morphologies of barium ferrite and hollow spherical carbon particles can be adjusted by controlling the amounts of synthetic compounds in the 8-12 GHz range. The results indicate that combining rod-shaped barium ferrite particles (900 ºC) and hollow spherical carbon particles in a thin epoxy coating improves impedance matching and wave attenuation. Notably, when the epoxy coating is 1.5-2 mm thick and contains 20% rod-shaped barium ferrite particles (900 ºC) and 1% hollow spherical carbon particles, reflection loss values of <-20 dB are observed at frequencies of 10-12 GHz.

Harnessing the Potency of Eco-Friendly Calcium Oxide Derived from Eggshells for Enhanced Photocatalytic Activity and Biocompatibility Evaluation in HepG2 Cell Line

Efforts towards sustainable development and pollution prevention are driving the exploration of bio-Calcium oxide (CaO) production from eggshell waste. This work investigates the thermal conversion of eggshell derived CaCO3 into CaO. Powder X-ray diffraction and Fourier transform infrared spectroscopy confirm CaO composition, displaying a cubic structure with 2.405 Å bond length and a mid-bond electron density of 0.2298 e/ų. Electron density studies corroborate this, revealing a three-dimensional distribution and one-dimensional profile. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirms spherical CaO particles and EDAX spectra displays the presence calcium and oxygen. UV absorption spectra reveal a 3.3 eV energy bandgap, showcasing CaO's photocatalytic potential. It demonstrates exceptional photocatalytic against congo red and methylene blue dyes, degrading them by 96.4% and 98%, respectively, via pseudo first-order kinetics. Additionally, CaO demonstrates promising anticancer activity against HepG2 liver cancer cells, with an IC50 value of 31.2 μg/mL, positioning it as a cost-effective and potent agent for both wastewater treatment and cancer therapy.

On the microstructural evolution and mechanical property development of additively manufactured AlCoCrFeNi2.1 eutectic high-entropy alloy with aging temperature

In this study, the microstructure and mechanical properties of a laser powder bed fusion processed eutectic high-entropy alloy, AlCoCrFeNi2.1, and the influence of aging temperature have been investigated. The as-printed material consists of a hierarchical cellular eutectic microstructure with γ cells and a B2 network along the cell boundaries. The γ matrix contains homogeneously distributed Al2O3 nanoparticles and sporadically distributed L12 long-range ordered (LRO) domains. Some B2 grains contain ultrafine body-centred cubic Cr-rich precipitates. Aging at 500–700 °C leads to disruption of the B2 network and coarsening of the B2 grains at the intersections of several cells and thinning of the rest of the regions. At 800 °C, the B2 cellular network completely disappears and turns into large isolated spherical or near-spherical B2 particles with the original γ cells being fully integrated. At 600 °C, numerous ultrafine γ′ nanoparticles form from the γ matrix and turn into elongated γ′ at 700 °C but completely disappear at 800 °C due to the formation of thermally more stable B2 precipitates. The as-printed samples show a high yield strength (YS∼ 1050 MPa) and good ductility (elongation ∼ 20 %) due to the strengthening effects from the LRO domains and the less deformable B2 and Al2O3 particles. Aging at 600–700 °C leads to significant strength improvement mainly owing to the γ′ particles. Aging at 800 °C results in a considerable decrease in YS but improves the ductility due to the disappearance of γ′ precipitates and the B2 cellular network.

Impact study of operating parameters on drying evolution of spherical tea particle under convective influence

Impact study of operating parameters on drying evolution of spherical tea particle under convective influence

Particle size effect on the thermoelastic behavior of composites—A comparative study between heterogeneous and homogenized beams

The particle size effect on the overall thermoelastic behavior of a composite containing many identical spherical particles reduces with the specimen-particle size ratio (SPR). When SPR is large enough, the effective stiffness converges, and the homogenized properties can represent the composite. This paper addresses two challenging questions: How large of an SPR is enough to reach the convergent results for different loading conditions, and whether is the critical SPR obtained from a uniform loading condition applicable to a nonuniform loading condition? When a uniform load is applied to a composite beam, the elastic moduli and thermal expansion coefficients can be calculated from the material’s response. When the beam is subjected to pure or thermal bending, the deflection can be predicted by the heterogeneous or homogenized beams. The inclusion-based boundary element method (iBEM) is developed for high-fidelity simulation of the many-particle systems. Given a volume fraction of particles, particle and beam size, and beam geometry, the local fields and the effective deformation are calculated for uniform and nonuniform loading conditions. The comparative study between a homogenized beam by the micromechanical approach and the numerical simulation of the heterogeneous particle system shows that a much larger SPR is required for thermal bending to reach a convergent result between the heterogeneous and homogenized beam. When the SPR is moderate, a cross-scale modeling method shall replace the micromechanical modeling to achieve accurate results.

Highly Active Immobilized Catalyst for Ethylene Polymerization: Neutral Single Site Y(III) Complex Bearing Bulky Silylallyl Ligand.

Exploring the surface organometallic chemistry on silica of highly electrophilic yttrium complexes is a relatively uncommon endeavor, particularly when focusing on tris-alkyl complexes characterized by Y-C σ-alkyl bonds. A drawback with this class of complexes once grafted on silica, is the frequent occurrence of alkyl transfer by ring opening of siloxane groups, resulting in a mixture of species. Herein, we employed a more stable homoleptic yttrium allyl complex bearing bulky η3-1,3-bis(trimethylsilyl)allyl ligand to limit this transfer reaction. This strategy has been validated by comparing the reactivity between [Y{η3-1,3-C3H3(SiMe3)2}3] and [Y(o-CH2PhNMe2)3] with SiO2-700, where the undesired alkyl transfer reaction occurred for [Y(o-CH2PhNMe2)3] leading to a bipodal [(≡SiO)2Y(o-CH2PhNMe2)] as major surface species, 2, while [Y{η3-1,3-C3H3(SiMe3)2}3] resulted selectively in a monopodal species, [(≡SiO)Y{η3-1,3-C3H3(SiMe3)2}2], 1. The materials obtained were characterized by DRIFT, solid state NMR, mass balance analysis and EXAFS. Catalyst 1 showed high activity compared to 2 in ethylene polymerization. The catalytic performance of this neutral catalyst 1 was extended to pre-industrial scale in the presence of hydrogen and 1-hexene. An unprecedented activity, up to 7400 gPE·gcat-1·h-1 was obtained even with very low concentration of scavenger AliBu3 (TIBA/Y = 1.2). The obtained HDPE exhibited desired spherical particle morphology with broad molar mass distribution.

Micrometric pyrite catalyzes abiotic sulfidogenesis from elemental sulfur and hydrogen

Hydrogen sulfide (H2S) in environments with temperatures below 100 °C is generally assumed to be of microbial origin, while abiotic H2S production is typically restricted to higher temperatures (T). In this study, we report an abiotic process for sulfidogenesis through the reduction of elemental sulfur (S0) by hydrogen (H2), mediated by pyrite (FeS2). The process was investigated in detail at pH 4 and 80 °C, but experimental conditions ranged between 40 and 80 °C and pH 4–6. The experiments were conducted with H2 as reducing molecule, and µm-sized spherical (but not framboidal) pyrite particles that formed in situ from the H2S, S0 and Fe2+ present in the experiments. Fe monosulfides, likely mackinawite, were identified as potential pyrite precursors. The absence of H2 production in controls, combined with geochemical modelling, suggests that pyrite formation occurred through the polysulfide pathway, which is unexpected under acidic conditions. Most spherical aggregates of authigenic pyrite were composed of nanometric, acicular crystals oriented in diverse directions, displaying varying degrees of organization. Although it was initially hypothesized that the catalytic properties were related to the surface structure, commercially sourced, milled pyrite particles (< 50 μm) mediated H2S production at comparable rates. This suggests that the catalytic properties of pyrite depend on particle size rather than surface structure, requiring pyrite surfaces to act as electron shuttles between S0 and H2.

Unveiling the impact of stabilization pretreatment on sodium storage performance in hard carbon

Stabilization pretreatment coupled with molecular cross-linking is commonly used to modify starch, aiming to obtain starch-based hard carbon materials with appropriate spherical particle sizes. Nevertheless, the impact of the intermediate stabilization process on its sodium storage performance remains unclear. Herein, a hard carbon material with no surface open pores, low specific surface area and abundant internal closed pores with thinner pore walls is successfully synthesized and exhibits significantly improved initial Coulombic efficiency and plateau capacity through a simple low-temperature pretreatment strategy, using renewable and cost-effective soluble starch as the raw material. Additionally, research indicates that an appropriate degree of disorder or defectiveness is conducive to forming a larger quantity of closed pores with thinner pore walls. Both excessively low and high defect levels are detrimental to the formation of closed pores. This work will encourage researchers to further focus on the impact of defectiveness on closed pores, which will promote the development of high-energy practical sodium-ion batteries.

Rotational and translational motions in a homogeneously cooling granular gas

A granular gas composed of monodisperse spherical particles was studied in microgravity experiments in a drop tower. Translations and rotations of the particles were extracted from optical video data. Equipartition is violated, the rotational degrees of freedom were excited only to roughly 2/3 of the translational ones. After stopping the mechanical excitation, we observed granular cooling of the ensemble for a period of three times the Haff time, where the kinetic energy dropped to about 5% of its initial value. The cooling rates of all observable degrees of freedom were comparable, and the ratio of rotational and translational kinetic energies fluctuated around a constant value. The distributions of translational and rotational velocity components showed slight but systematic deviations from Gaussians at the start of cooling.