Particuology最新文献

To explore the influence of the meso-mechanical behaviors of the wet coal dust layers on the contact stiffness of mechanical bonding surfaces, a three-body contact model incorporating an interface with wet coal dust was constructed based on breakage theory. The model considered the mechanical surface morphology and contact characteristics of the wet coal dust. The force chain evolution laws of the wet coal dust layer were elucidated under the effects of gap filling and the cover layer, and the bearing characteristics of the three-body contact bonding surfaces were revealed by quantitative analyses of the number, length, collimation coefficient, and coordination number of the force chains within the wet coal dust layer. Finally, the three-body normal contact stiffness under various preload forces was computed and experimentally validated. The results demonstrate that the external load transfer path of the three-body contact bonding surfaces was from mechanical surface (macroscopic stress) to wet coal dust layer (mesoscopic force chains) and then to mechanical surface (peaks and valleys). The interactions among these three elements contributed to transforming the distributions of the macroscopic stresses and mesoscopic force chains to the locations at the peaks and valleys of the mechanical surface. Among them, the proportion of short force chains in the wet coal dust layer increased from approximately 0.8% to 91%, while the proportion of long force chains exhibited an opposite changing trend. The force chain collimation coefficient initially increased and subsequently stabilized, reaching a maximum value of 0.93. A large number of broken, small particles in the wet coal dust layer mainly served to fill the gaps among large particles. The maximum relative error between the experimental and simulated values on the three-body contact stiffness is 7.26%, indicating that the simulation results can be an approximate substitute for the experimental results with a certain degree of accuracy and practicality. The research results are of great significance for understanding the contact characteristics of mechanical surfaces containing particulate media.

The generation of reactive oxygen species (ROS) at the tumor site to induce destruction is emerging as a novel strategy for cancer treatment, which involves photodynamic therapy (PDT). Nevertheless, tumors typically create a hypoxic environment and are equipped with an endogenous antioxidant defense system that could potentially impede the efficiency of the therapeutic approach. To overcome these drawbacks, herein, a tumor microenvironment-responsive the ND-PAA-CD-Ce6@MnO₂ (NPCC@M) delivery system was fabricated by disulfide bond coupling chlorin e6 (Ce6) to nanodiamond (ND) and further wrapped by MnO₂ nanosheets to facilitate PDT. The use of disulfide bond not only stabilizes Ce6 in the blood circulation to prevent premature leakage, but also destroys the antioxidant barrier of overexpressed glutathione (GSH) in tumor cells. Moreover, the outer MnO₂ was rapidly degraded by the endogenous hydrogen peroxide (H₂O₂) in the acidic pH and GSH within the tumor cells, which leads to an abundance of O₂ and while increases the level of ¹O₂ under laser irradiation. The results eventually broke the redox homeostasis and attenuate hypoxia, thereby inducing apoptosis and necrosis of tumor cells. Detailed in vitro and in vivo biological effect has revealed a good biosafety profile and a high tumor suppression effect. Such a novel ND-based system with tumor microenvironment-modulating capability to elevate oxygen content and promote GSH consumption in tumor cells opens new opportunities for enhanced ROS treatment paradigms.

In this study, glucose and NH₄F were utilized as sources of carbon and fluorine, respectively, for the synthesis of LiMn_0·6Fe_0·4PO₄ (LMFP) nanoscales. These nanoscales were subsequently modified with varying levels of fluorine-doped carbon through co-precipitation and mechanical ball milling processes. The LMFP, incorporating carbon and varying levels of fluoride ions, exhibit higher specific discharge capacities at 0.2 Cand electrochemical characteristics compared to the original LMFP coated solely with carbon. The inclusion of fluorine-doped carbon in the composite material creates numerous pathways for expeditious electron transfer. Moreover, the partial formation of metal fluoride at the interface between the surface of LMFP and the layer of carbon coating doped with fluorine enhances the reduction in the charge-transfer resistance. The modified ferromanganese phosphate cathode material reveals an outstanding discharge capacity displaying a reversible discharge specific capacity value of 131.73 mA h g⁻¹ at 10C and 154.6 mA h g⁻¹ at 0.2C, due to its unique structure.

Conventionally synthesized silver nanoparticles (AgNP) imposed an alarming effect on the environment and caused toxicity to humans. However, the use of zeolite (zeoY) as a support system could increase its biocompatibility and reduce its toxicity. Hence, green synthesis of AgNP using Persicaria odorata leaves extract supported on zeolite Y has been prepared by an in situ synthesis technique. The phytochemical compounds in the optimized leaf extract concentration of 1% and volume of 0.9 mL reduced the silver ions to AgNP within the zeolite Y pores. Morphological observation revealed the incorporation of AgNP in the zeolite Y (average size: 18.51 nm). The release of AgNP exhibited antibacterial activity on C. acnes at a concentration lower than 1 g L⁻¹ which is also dependent on the electrolyte. AgNP-zeoY promoted cell proliferation in vitro and it has a non-irritating effect when tested in the in vivo skin irritation model.

Particle entrainment is an inevitable phenomenon in pipeline systems, especially during the development and extraction phases of oil and gas wells. Accurately predicting the critical velocity for particle transport is a key focus for implementing effective sand control management. This work presents a semi-supervised learning–deep hybrid kernel extreme learning machine (SSL-DHKELM) model for predicting the critical velocity, which integrates multiple machine learning theories including the deep learning approach, which is adept at advanced feature extraction. Meanwhile, the SSL framework enhances the model's capabilities when data availability is limited. An improved slime mould algorithm is also employed to optimize the model's hyperparameters. The proposed model has high accuracy on both the sample dataset and out-of-sample data. When trained with only 10% of the data, the model's error still did not increase significantly. Additionally, this model achieves superior predictive accuracy compared to existing mechanistic models, demonstrating its impressive performance and robustness.

This work investigates the flow and agglomeration behaviors of battery grade Li₂CO₃ powder and the influence of stearic acid surface modification. The degree of agglomeration is directly related to the uniformity of Li₂CO₃ and its powder mixtures. According to the Chinese National Nonferrous Metal Industry Standard, battery grade Li₂CO₃ powder has D₅₀ equal to 3–8 μm which belongs to a micron-sized superfine powder. Therefore, with the extension of storage time, the serious agglomeration phenomenon occurs due to the large specific surface area and rough and irregular powder particles. The Hausner ratio (HR) of the unmodified sample increases from 1.14 to 1.41, and the corresponding flowability is classified as good to poor. Instead, among samples with doping stearic acid, the optimum amount of it is 0.10 wt% which exhibits an extremely stable HR value from 1.14 to 1.16. Meanwhile, after 156 days, the repose angle (AR) obtained for samples without surface modification and using 0.10 wt% stearic acid are calculated to be 49° and 28°, respectively. Based on the values of HR and AR, the flowability of the unmodified sample is poor while the sample modified with 0.10 wt% of stearic acid still maintain excellent powder flow property. Moreover, The LiMn₂O₄ cathode material synthesized from modified Li₂CO₃ powder with a stearic acid content of 0.10 wt% exhibits good crystallinity and comparable electrochemical performance to that prepared by commercial Li₂CO₃. These results indicate that stearic acid has the potential to be an ideal modifier for battery grade Li₂CO₃ powder that needs to be kept for a long time.

Tumor immunotherapy, particularly cancer vaccines, holds promise for combating cancer by harnessing tailored immune responses against malignant cells. However, conventional approaches face challenges in efficiently delivering antigens for optimal immune activation. Emulsion adjuvants, like MF59, enhance cellular uptake but struggle to induce robust CD8⁺ T cell responses. Here, we introduce a novel strategy employing a water-in-oil-in-water (W/O/W) multiple Pickering emulsion (mPE) for antigen delivery. The mPE, utilizing biocompatible, pH-sensitive particles, encapsulates antigens within the inner water phase, ensuring enhanced intracellular processing and dictating the intracellular fate of antigens for improved cross-presentation. In vitro and in vivo studies demonstrated that mPEs induced robust dendritic cells activation and antigen cross-presentation, leading to a significantly enhanced immune response. Notably, calcium phosphate-stabilized mPE (CaP-mPE) illustrated the more robust IFN-γ⁺ T cell responses. In comparison with traditional surfactant-stabilized multiple emulsions, CaP-mPE significantly inhibit tumor growth and effectively prolong the survival of tumor-bearing mice. This innovative approach offers a promising avenue for the development of effective cancer vaccines with potent cellular immune responses.

For the high-temperature and short-contact time gas-solid reaction process, riser and downer are considered appropriate reactors. To realize an intensive and complete mixing of reactants with catalysts, the feed raw is always introduced in the form of high-speed jets. In this study, in order to investigate the mixing effects of different types of high-speed jets in riser and downer, traceable ozone is injected with the high-speed feed jets to react with catalyst particles. By detecting the decomposition of ozone, the gas-solid mixing and reaction in riser and downer under the influence of both co-current and counter-current injections are analyzed. The relative ozone concentration is used to reflect the location reaction extent and its radial nonuniformity index is proposed to compare the results in riser and downer. It is found that the jet influence zone in downer provides a relatively better environment for the mixing of feed jets with catalysts. In the riser, introduction of counter-current injections could improve the uniformity of gas-solid mixing in the initial contact region of feed with catalysts.

Gas-solid Fluidized Bed Coal Beneficiator (GFBCB) process is a crucial dry coal beneficiation fluidization technology. The work employs the GFBCB process alongside a novel Geldart A^– dense medium, consisting of Geldart A magnetite particles and Geldart C ultrafine coal, to separate small-size separated objects in the GFBCB. The effects of various operational conditions, including the volume fraction of ultrafine coal, the gas velocity, the separated objects size, and the separation time, were investigated on the GFBCB's separation performance. The results indicated that the probable error for 6∼3 mm separated objects could be controlled within 0.10 g/cm³. Compared to the traditional Geldart B/D dense medium, the Geldart A/A^– dense medium exhibited better size-dependent separation performance with an overall probable error 0.04∼0.12 g/cm³. Moreover, it achieved a similar separation accuracy to the Geldart B/D dense medium fluidized bed with different external energy for the small-size object beneficiation. The work furthermore validated a separation density prediction model based on theoretical derivation, available for both Geldart B/D dense medium and Geldart A/A^– dense medium at different operational conditions.

The present study concerns understanding the effect of process parameters on the characteristics and flowability of nanocrystalline CoNiCrAlY powder synthesized by mechanical milling. Mechanical milling has been conducted in a planetary ball mill with tungsten carbide (WC) ball, with ball to powder ratio of 10:1 at 300 rpm speed, using 1% stearic acid and toluene as process control agent (PCA) with time varying from 10 h to 36 h. The synthesized nanocrystalline powder were characterized by Scanning Electron Microscopy, X-ray Diffraction technique, X-ray Photoelectron Spectroscopy, and Differential Scanning Calorimetry. Subsequently, flowability in terms of Hausner ratio was assessed by Tap Density Tester. Average particle size of the powder was found to decrease from 33 μm to 22 μm after 10 h of milling and further increases to 43 μm and 38 μm after 25 and 36 h of milling, respectively, in stearic acid medium. However, in toluene medium particle size continuously decreases from 33 μm to 9.7 μm with increasing milling time. The particle morphology changes from spherical to platelet shape at low milling hours in both of the media. After 25 h of milling, the shape of the particles is nearly spherical for stearic acid and irregular for toluene used as a PCA. Crystallize size was found to decrease with increasing milling time from 147 nm to 7.7 nm and to 6.4 nm in stearic acid and toluene media, respectively. There was presence of γ, γʹ, β, hcp-Co, Al₂O₃ and AlOOH phases on the powder particles milled in both the medium. The measured Hausner ratio of the powders was found to vary from 1.18 to 1.32 in stearic acid medium, and was found to increase with increasing milling time. On the other hand, in toluene media flowability decreases (Hausner ratio increases from 1.33 to 1.44) with increasing milling time.