Microstructure Of Particles Research Articles

A Spray-Dried Self-Stabilizing Nanocrystal Emulsion of Traditional Chinese Medicine: Preparation, Characterization and ex vivo Intestinal Absorption

AbstractSalvia miltiorrhizae (Danshen, the rhizome of Salvia miltiorrhiza Bge.) and Chuanxiong rhizome (Chuanxiong, the rhizome of Ligusticum chuanxiong Hort.) are two traditional Chinese medicines that have been widely used for the treatment of cardiovascular and cerebrovascular diseases. However, formulation development is difficult due to the complexity of the active ingredients, particularly the water-insoluble tanshinones and volatile oil of Chuanxiong rhizome, which cannot be absorbed via oral administration in conventional dosage forms. This study aimed to develop a self-stabilized nanocrystal emulsion co-loading the water-soluble, insoluble, and volatile active ingredients of Salvia miltiorrhizae and Chuanxiong rhizome to improve the bioavailability of the drugs. In this work, a high-pressure homogenization method was used to prepare a self-stabilizing nanocrystal emulsion. The emulsion was then spray-dried using hydroxypropyl-β-cyclodextrin. The dispersibility and storage stability of the spray-dried emulsion, the particle size and morphology of the emulsion droplets, and the drug content and phase distribution of the reconstituted emulsion were evaluated. An everted intestinal sac model was established, and high-performance liquid chromatography was used to determine the concentration of six active components (ferulic acid, salvianolic acid B, senkyunolide A, ligustilide, cryptotanshinone, and tanshinone IIA) and to assess the cumulative uptake amount of the drug and the apparent permeability coefficient. A mixture of the crude materials of tanshinones extract, total salvianolic acid, ferulic acid, and volatile oil of Ligusticum Chuanxiong was used as a control. The results showed that the spray-dried emulsion can be easily reconstituted into a uniform submicron emulsion with no significant changes in particle size, morphology, and microstructure of the emulsion droplets compared with the original emulsion before drying. The self-stabilizing nanocrystal emulsion significantly improved the intestinal absorption of water-insoluble components (tanshinone IIA, cryptotanshinone, and ferulic acid), and volatile oil components (senkyunolide A and ligustilide). Overall, the spray-dried self-stabilizing nanocrystal emulsion represents a potential oral formulation for Salvia miltiorrhiza and Chuanxiong rhizoma.

The cumulative breakage probability by repeated stressing of γ-Al2O3 granules

The cumulative breakage probability by repeated stressing of γ-Al2O3 granules, was described using two models. The first model, where breakage probability by single stressing of granules remains constant, was not suitable for repeated stressing. The model was inappropriate to determine the change in the particle’s microstructure during stressing. Whereas in the second model, the hardening effect to be taken into account during stressing and was defined by a reduction factor of breakage probability. The deformation behavior of granules was used to indicate the change of microstructure of particles during stressing. In this case, the stiffness of the granules increased by means of plastic yielding and consolidation granules. In the compression test, the stiffness increased rapidly through fixed treatment. Meanwhile, in the case of rotated treatment the stiffness was significantly unaffected, as it was randomly distributed throughout the particle surface. Consequently, the cumulative breakage probability of rotated granules was lower compared to the fixed one.

Reversible Configurations of 3-Coordinate and 4-Coordinate Boron Stabilize Ultrahigh-Ni Cathodes with Superior Cycling Stability for Practical Li-Ion Batteries.

Ultrahigh-Ni layered oxide cathodes are the leading candidate for next-generation high-energy Li-ion batteries owing to their cost-effectiveness and ultrahigh capacity. However, the increased Ni content causes larger volume variations and worse lattice oxygen stability during cycling, resulting in capacity attenuation and kinetics hysteresis. Herein, a Li2SiO3-coated Li(Ni0.95Co0.04Mn0.01)0.99B0.01O2 ultrahigh-Ni cathode that well-addresses all the above issues, which is also the first time to realize the real doping of B ions is demonstrated. The as-obtained cathode delivers a reversible capacity of up to 237.4 mAh g-1 (924 Wh kg-1 cathode) and a superior capacity retention of 84.2% after 500 cycles at 1C in pouch-type full-cells. Advanced characterizations and calculations verify that the boron-doping is existed in terms of 3-coordinate and 4-coordinate configurations and their high electrochemical reversibility during de-/lithiation, which greatly stabilizes oxygen anions and impedes Ni-ion migration to Li layer. Furthermore, the B-doping engineers the primary particle microstructure for better relaxing the lattice strain and accelerating Li-ion diffusion. This work advances the energy density of cathode materials into the domain of above 900 Wh kg-1, and the concept will inspire more intensive study on ultrahigh-Ni cathodes.

Preparation of C-S-H seeds from waste glass powder and its effect on early performance of cement paste

This study investigates the hydrothermal synthesis of calcium silicate hydrate (C-S-H) seeds using nano-size glass powder (NGP) derived from siliceous raw materials and CaO as the calcareous precursor. The influence of varying NGP concentrations on the particle size, microstructure, and phase composition of the C-S-H seeds was systematically analyzed. The synthesized C-S-H seeds were subsequently employed as additives to evaluate their effects on the early hydration process and compressive strength development of cement paste. The results indicate that increasing the NGP concentration from 0.2 mol/L to 0.8 mol/L leads to an exponential increase in the median particle size of the C-S-H seeds from 147 nm to 1328 nm and a corresponding morphological transformation from flocculent to granular structures. Additionally, the purity of the C-S-H sample decreased from 74.8% to 54.5% as the NGP concentration increased. The addition of C-S-H seeds can increase the 12h compressive strength of cement pastes by 15.5%–53.5%. This improvement is due to the accelerated early hydration kinetics induced by the C-S-H seeds, which act as nucleation sites, thereby increasing the nucleation and growth rates by 31.4% and 53.2%, respectively.

Effect of Rare Earth Y on the Microstructure, Mechanical Properties and Friction of Sn-Babbitt Alloy

Babbitt alloy is a bearing material with excellent properties, including good anti-friction wear resistance, embeddedness, corrosion, and compliance, as well as sufficient bearing capacity. However, with the development of engines to have high speed and heavy load, the use of Babbitt alloy as a bearing material exposes its weaknesses of low bearing capacity, insufficient fatigue strength and a sharp decline in mechanical properties with an increase in working temperature. Therefore, its application scope is gradually narrowed and subject to certain limitations. Improving the tensile strength and wear resistance of tin-based Babbitt alloy is of great significance to expanding its application. In this study, tin-based Babbitt alloy was taken as the main research object; the particle size, microstructure, mechanical properties, and friction were systematically studied after the single addition of Y-Cu composite in tin-based Babbitt alloy liquid. The wear performance and the strengthening, toughening and wear mechanisms of tin-based Babbitt alloy were investigated under the action of Y in order to prepare a high-performance tin-based Babbitt alloy for bimetallic bearing. It was found that when rare-earth Y was added to the Babbitt alloy body, the wear properties were greatly improved.

How does the coupled action of freeze - Thaw and acidification affect the release of toxic elements from indigenous Zn smelting slags?

Under complicated field conditions, such as the coupled effects of freeze - thaw cycles (FTs) and acidification, the leaching behavior of potentially toxic element (PTEs) from indigenous Zn smelting slags (ZSS) was intricately connected to the mineralogy (e.g., the composition, assemblage, microstructure of mineral particles). In this study, FTs tests were carried out to explore the interactions between PTEs release and ZSS mineralogy. Subsequently, advanced characterization techniques were adopted to quantify the mineralogy and microstructure of ZSS. The results indicated that ZSS were mainly composed of silicate minerals (e.g., quartz, biotite and chlorite) and secondary Fe (III) oxyhydroxides (e.g., magnetite and limonite), accounting for 67.48% and 24.23%, respectively. The occurrence mode analysis revealed that 81.95% of As, 21.31% of Pb and 7.77% of Zn were hosted in limonite. About 37.89%, 59.34% and 34.50% of Cd, Pb and Zn were associated with carbonate bound fractions. Under FTs interacting with different pH conditions, the leaching concentrations of As, Cd, Cu, Pb and Zn did not significantly increase with the increase in FTs and pH. The microstructure damage of mineral particles in ZSS with the higher porosity was caused by both FTs and proton corrosion. More importantly, the geochemical modeling results suggested that the precipitation of hematite and magnetite might have little impacts on PTEs release under FTs and FTs with acidification. This work would provide a deeper understanding of PTEs release from smelting waste slags under complex physicochemical interactions.

Retraction: Effects of thermal aging atmospheres on oxidation activity, element composition and microstructure of diesel soot particles.

[This retracts the article DOI: 10.1039/D3RA05340G.].

Autoencoder-based inverse design and surrogate-based optimization of an integrated wet granulation manufacturing process

In pharmaceutical manufacturing, integrating model-based design and optimization can be beneficial for accelerating process development. This study explores the utilization of Machine Learning (ML) techniques as a surrogate model for the optimization of a three-unit wet-granulation based flowsheet model for solid dosage form manufacturing. First, a reduced representation of a wet granulation flowsheet model is developed, incorporating a granulation and milling process, along with a novel dissolution model that accounts for the effect of particle size, porosity, and microstructure on dissolution rate. Two optimization approaches are compared, including an autoencoder-based inverse design and a surrogate-based forward optimization. Both methods address the bi-objective problem of maximizing dissolution time and product yield by identifying the optimal granulation and mill process parameters. For this case study, both approaches were effective and incurred a similar computational cost, averaging under 4 s. However, the autoencoder approach offers an advantage through dimensionality reduction, a feature not available in surrogate-based optimization. Dimensional reduction is particularly beneficial for complex process designs with numerous inputs and outputs. The lower dimensional representation helps improve process understanding through enhanced visualization of the process design space and facilitates feasibility studies involving multiple constraints. The autoencoder-based inverse design introduced in this work showcases an implementation of AI and ML in pharmaceutical process development, demonstrating the potential to enhance process efficiency and product quality in complex manufacturing scenarios.

Research on preparation and stability of high viscosity carbon nanotube-modified PAO20-based magnetic fluids

The preparation of high-performance magnetic fluids with high viscosity, high saturation magnetization and high stability, has remained a pivotal challenge limiting the advancement of associated applications. In the present study, we synthesized modified magnetic nanoparticles through an innovative approach combining in-situ carbon nanotube (CNT) generation with chemical co-precipitation. These nanoparticles were then co-coated with OA/PIBA, resulting in the preparation of advanced PAO20-based magnetic fluids. The effects of CNT modification on particle microstructure and magnetic properties were studied by transmission electron microscopy and vibrating sample magnetometer, the magnetoviscous properties of magnetic fluids were studied by a rotating rheometer equipped with a magnetic field module, and the stability of the prepared magnetic fluids under a strong magnetic field was tested by a self-made LC oscillation circuit. The results show that the saturation magnetization of the prepared magnetic fluids surpasses 32 emu/g, while their viscosity reaches a remarkable 6625 mPa·s (at 0.24 T, 100 1/s shear rate and 25 °C), which is significantly higher than that of traditional magnetic fluids (usually about 100 mPa·s). Furthermore, when exposed to a 0.6 T magnetic field, the magnetic fluids could exhibit Rosensweig instability that persists for over 468 h. The stability is at least 93 times superior to that of unmodified PAO20-based magnetic fluids. Based on these encouraging results, it can be fully predicted that the CNT-modified PAO20-based magnetic fluids developed in this study will play a pivotal role in various applications, including sealing, lubrication, and vibration reduction. Their exceptional properties will hold immense promise for numerous engineering applications.

Geometric modelling of corrosion inhibitor pigments in active protective coatings based on SR-nano-CT images

This paper reports on an essential step towards accelerating the development of new, environmentally friendly active protective coatings by structure optimization. The complex microstructure of the pigment particles within a coating have been observed non-destructively in 3D by nano-computed tomography using synchrotron radiation. For the first time, a stochastic geometry model is fitted based on spatial geometric features of the particles observed in the 3D images. The typical cell of a random Gibbs-Laguerre tessellation is used to model the particles' polyhedral shapes as well as the observed joint size and aspect ratio distributions.

Effects of raw materials on microstructure and mechanical properties of second phase particles reinforced W[sbnd]Re composites

Combined strengthening of micron and nanoscale second phase particles is of great significance for improving the comprehensive properties of tungsten (W) based refractory alloys. In this work, with the addition of raw HfC, HfH2 and carbon powders, three types of W-3 wt%Re-0.3 wt%HfC (WRH) composites were fabricated by powder metallurgy and rotary swaging. The microstructure and mechanical properties of three WRH samples were investigated comparatively. Results show that three WRH samples are constituted by W matrix, HfO2 and HfC second phase particles. When HfH2 powder is served as the raw material, the obtained two kinds of composites show the microstructure configuration with a micro-nano combined second phase particles. That is, some larger HfO2 particles are located at the matrix grain boundaries and fine nanoscale HfC particles are inside W matrix grains. Based on it, both composites exhibit the better overall performance. When the carbon powder ratio reaches 0.03 wt%, WRH composite shows the smallest average matrix grain size and a smaller size of second phase particles inside the matrix grains, and thereby gaining the better ultimate tensile strength and hardness. As carbon powder ratio rises to 0.07 wt%, WRH sample presents an excellent elongation. Besides, the formation mechanisms of HfO2 and HfC particles, as well as the correlation between microstructure and mechanical properties, were discussed particularly.

Through-thickness particle distribution, microstructure evolution and tribological performance of B4C/BN-AA6061 composite via friction stir processing

In this study, we investigated the interactions between BN and B4C particles in particle reinforced Al matrix composites (PRAMCs) during friction stir processing (FSP), focusing on particle distribution, microstructure evolution, hardness, and wear resistance. PRAMCs were fabricated with BN accounting for 0 wt%, 10 wt%, 20 wt%, 30 wt% and 100 wt% of the reinforcement particles. Optical microscopy (OM) and scanning electron microscopy (SEM) revealed that particle distribution varied through thickness, becoming more inhomogeneous with increasing BN mass ratio. The most uniform distribution was noted 3 mm beneath the surface, particularly in the BN-30%-3 mm sample. This sample also showed improved homogeneity in B4C distribution, as confirmed by the box-counting (BC) method. The refined grain structure due to particle stimulated nucleation (PSN) and Zener pinning contributed to an average hardness of 96.67 HV in the BN-30%-3 mm sample, significantly enhancing wear resistance. The wear rate in this sample was reduced by 97.2 % compared to the FSP-3 mm sample, likely due to finer grains, higher hardness, and increased reinforcement, which collectively reduced adhesion and fatigue wear.

Effect of the SiC powder microscopic morphology on properties of Si/SiC ceramics prepared by spark plasma sintering

AbstractTo solve the problem that Si was volatile and dense Si/SiC ceramics were difficult to achieve by spark plasma sintering (SPS) under a low sintering temperature and pressure, three kinds of SiC powders were used for particle grading and then ball‐milled with different time to further change and regulate their particle size and morphology, and finally nearly dense Si/SiC ceramics were prepared by SPS. The effect of milling time on particle size, morphology, tap density, phase, and microstructure of the SiC powders, as well as on bulk density, microhardness, thermal conductivity, phase, and microstructure of the Si/SiC ceramic, was researched. When the mixed SiC powders were ball‐milled for 12 min, the bulk density, microhardness, and thermal conductivity of Si/SiC ceramic were 2.96 g/cm3, 22.95 GPa, and 152.84 W/(m K), respectively. Ball milling changed the particle gradation and micro‐powder morphology and then affected the powder particle stacking state. Forming continuous pore channels was conducive for the volatile liquid Si to flowing and filling pores in a short time, resulting in denser Si/SiC ceramics at a lower sintering temperature and pressure. This study was useful for the preparation of ceramics containing volatile liquid phase by SPS.

Mathematical analysis of isothermal study of reverse roll coating using Micropolar fluid

This article demonstrates a mathematical model and theoretical analysis of the Micropolar fluid in the reverse roll coating process. It is important because micropolar fluids account for the microstructure and microrotation of particles within the fluid. These characteristics are significant for accurately describing the behavior of complex fluids such as polymer solutions, biological fluids, and colloidal suspensions. First, we modeled the flow equations using basic laws of fluid dynamics. The flow equations are made modified using low Reynolds number theory. The simplified equations are solved analytically. The exact expression for velocity and pressure gradient are obtained, while pressure is calculated numerically using Simpson Rule. Graphical depictions are carried out to comprehend the impact of the newly emerged physical constraints. The influence of micropolar and microrotation parameters on the velocity, pressure and pressure gradient are elaborated with the help of different graphs.

Molecular interaction of cyclodextrins with cellulose nanocrystals: A new venue for improving the functional properties of Pickering emulsions

The design of functional delivery systems is essential for storing and releasing active components. Inspired by the structure of Nepenthes mirabilis, cellulose nanocrystals (CNC) cooperate with cyclic α-cyclodextrins (α-CD), β-cyclodextrins (β-CD), and γ-cyclodextrins (γ-CD) to form nanocomposites at different mass ratios for the delivery the Mosla chinensis essential oils (EO)-loaded Pickering emulsions (PE), respectively. Characterization methods including FT-IR, TG, XPS, AFM, XRD, and three-phase contact angle were used to analyze the structure of the nanocomposites. The molecular docking and molecular dynamic simulation results revealed that the most hydrogen bonds were formed between β-CD and CNC, but the tendency for γ-CD and CNC to bond with hydrogen bonds was stronger in the molecular dynamic simulation. Subsequently, the physicochemical properties of emulsions stabilized by CNC/CDs nanocomposites were characterized through particle size, potential, microstructure, long-term stability, rheology, and aqueous phase distribution indexes. The results showed that the different mass ratios CNC/α-CD and CNC/β-CD nanocomposites stabilized PE had smaller droplet scales and better stability. While CNC/γ-CD nanocomposites had a negative effect on the emulsion. The in vitro release results showed that the emulsions stabilized by CNC/CDs nanocomposites had a slow-release rate for EO by diffusion. The simulated gastrointestinal release showed that CNC/β-CD-PE had the highest bioavailability. Moreover, CNC/β-CD-PE reduced the minimal inhibitory concentration of EO by a mechanism that disrupts the membrane structure of bacteria. Therefore, the introduction of β-CD may be an effective alternative in regulating the physical properties, function, and stabilization of CNC-based PE. These findings provide a scientific basis for the rational structural design of delivery systems for the encapsulated aroma molecules.

Study on physical and mechanical properties of high-grade highway subgrade slate in permafrost region under freeze–thaw cycles

The subgrade crushed-rocks of Gonghe-Yushu (Gongyu) Expressway in Qinghai Province are seriously weathered, resulting in a series of pavement diseases. Among the weathered crushed-rocks, the weathering degree of slate is particularly serious, and its physical and mechanical properties, weathering resistance and applicability are not clear. Therefore, this paper takes the slate in the subgrade crushed-rocks of Gongyu Expressway as the research object, and drills the core of the slate rock block to make a cylindrical standard sample, and uniaxial and triaxial compression tests, nuclear magnetic resonance tests, and electron probe micro-analysis tests were performed on it within 50 freeze–thaw cycles (FTC) under saturated conditions. According to the test results, the mass, longitudinal wave velocity, and strength of the slate specimens all decrease with the increase of the number of FTC, the cohesion (C)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$({\ ext{C}})$$\\end{document} increases first and then decreases, and the change trend of internal friction angle (φ) is completely opposite to the cohesion. The FTC has an expansion effect on the pores of the slate specimens, and the microstructure of the rock particles on the specimen’s surface is removed and becomes smooth. The results of mechanical tests are used in the Hoek–Brown (H-B) strength criterion, and a unified expression of the H-B criterion suitable for slate in permafrost regions is established. The above conclusions can provide some construction reference and maintenance of high-grade highways in cold regions.

Energy-size relationship and starch modification in planetary ball milling of quinoa

The effects of speed (250–450 rpm) and time (10–50 min) on milling energy (E), particle size distribution (PSD), crystallinity degree (CD), damaged starch (DS), microstructure, hydration and pasting properties of flours obtained in a planetary ball mill (PBM) were investigated. As increasing milling severity quinoa flours showed polydispersed PSD (peaks at 417, 40 and 2 μm) with a shift towards smaller size and greater dispersion (Span: 3.0–5.2) as well as particles with rounded edges and polished surfaces (SEM images). The relationship E − D50 were satisfactorily predicted by the Walker's equation. The hydration tests as function of temperature and milling conditions revealed a complex flour behavior due to differences in PSD, composition, and DS content. The increasing milling energy caused a decrease in peak viscosity (PV), trough viscosity (TV) and final viscosity (FV) of up to 36%, 29%, and 25%, respectively. Significant correlations between flour attributes were found (DS-CD, r = −0.83, p < 0.01; PV-D50, r = 0.92, p < 0.01; TV-D50, r = 0.94, p < 0.01; FV-D50, r = 0.90, p < 0.01) denoted the increase of starch degradation as milling severity rises. These results can be used to improve the manufacture and the selection criteria of quinoa flour with specific functional attributes.

Development of Efficient Ink Dispersion Process for Solid-State Electrolyte and Electrode Manufacturing

All-solid-state lithium batteries (ASSBs) have several advantages over lithium-ion batteries (LIBs) such as higher safety thresholds associated with solid electrolytes (SEs) and the possibility of using lithium metal or silicon anodes to achieve comparatively higher energy and power density. The SE can also prevent chemical interactions with dissolved active materials, and thus solve the issue of long-term instability of LIBs. However, there are also challenges associated with ASSBs manufacturing, such as local stress and contact-loss between SE and active materials in cathodes due to active material “breath”, poor contact and high ionic resistance at the SE-cathode interface, difficulty in fabricating thin SEs, and the absence of scalable and cost-effective manufacturing processes (J. Janek and W.G. Zeier, Nature Energy 8 (2023): 230-240). A key to tackling these issues begins with ink formulation for electrolyte and cathode coating, including ink compositions and rheological properties.In this study, we report the influence of ink preparation methods and conditions on the solid-state electrolyte and cathode coating qualities, where lithium lanthanum zirconium oxide (LLZO) and lithium nickel manganese cobalt oxide (NMC) are used as model systems. Various mixing methods, such as acoustic wave mixing, high-speed off-axis mixing, and thin film mixing, are compared. Their influence on ink viscosity and particle dispersion, coating thickness and microstructure uniformity, and electrolyte and electrode electrochemical properties will be discussed.

Novel nanoparticle composed by Ovalbumin-OSA modified pectin-rutin for improving the stability of Monascus pigments

To improve the resistance of Monascus pigments (MPs) to adverse environmental factors, a nanoparticle carrier was constructed using ovalbumin, rutin and pectin modified by octenyl succinic anhydride. According to the determination of particle size, ζ-potential and microstructure, the composite nanoparticles exhibited the "core-shell" structure. Specifically, the ovalbumin core was encapsulated by the modified pectin adsorbed with rutin. Spectroscopic analysis demonstrated that electrostatic interactions, hydrogen bonding and hydrophobic interactions between wall materials and MPs were the main driving forces to form composite nanoparticles. The stabilities of light, thermal and storage of MPs were significantly enhanced after encapsulation due to the physical barrier effect of the wall materials against external disturbances and the multiple functions of rutin, including free radical scavenging, absorption of partial UV and scatter light, and possible co-pigmentation effects with MPs. Moreover, the composite nanoparticles exhibited higher inhibition activity against pancreatic lipase and antioxidant activity compared with those of free MPs. The results provided an ideal way to develop new MPs products, which had long-lasting and stable performance during food processing and storage.

Synthesis of Silica Particles with Controlled Microstructure via the Choline Hydroxide Cocatalyzed Stöber Method.

This study investigates the utilization of choline hydroxide as a cocatalyst in the Stöber method to synthesize silica particles with controlled microstructure. Under low ammonia concentration, we add a robust organic base choline hydroxide and systematically explore the influence of choline hydroxide concentration on the hydrolysis and condensation equilibrium of tetraethyl orthosilicate (TEOS). Through the rational control of the water content, we significantly enhance both the size range and polydispersity of the resulting silica particles. Taking advantage of the regulated microstructure induced by controlled hydrolysis and condensation catalyzed by choline hydroxide, we achieved silica particles with hollow structures through hot water etching, exhibiting significantly enhanced surface area. These findings demonstrate the versatility of choline hydroxide as a cocatalyst in tailoring the microstructure of silica particles. In addition, due to its reducing ability and biocompatibility, which are not shared by other reported catalysts, the use of choline hydroxide opens up opportunities for applications in catalysis, sensing, and drug delivery.