Nanoscale Particles Research Articles

Raman Characterization of Plastics: A DFT Study of Polystyrene.

Plastic materials are ubiquitous and raise concerns about their impact on health and the environment. To address these concerns, it is crucial to characterize the structural, size, and textural properties of plastics throughout their lifecycle from production to degradation. Raman spectroscopy appears as a valuable tool for this purpose, offering speed, robustness, and sensitivity to nanoscale and amorphous particles. In order to be properly used for plastics, the Raman response of reference materials needs to be carefully assessed, with the literature on such assessments being scarce. This study addresses this gap by using theoretical calculations to generate ab initio spectra for polystyrene, a reference material. The aim is to explain the origins of the spectral peaks and their consistency across various compositions and structures using linear ordered polymeric and finite amorphous models. The CRYSTAL package is employed to obtain full Raman spectra based on a careful benchmark of computational settings. While some peaks are present across all spectra and can serve for calibration, others exhibit structure-dependent behavior, enabling polymer identification. We conclude that Raman spectroscopy is a well-suited technique for plastics characterization provided that a careful analysis of signal origin is conducted to fully interpret the spectra and deploy applications.

Removal of arsenic from water by silver nanoparticles and Fe-Ce mixed oxide supported on polymeric anion exchanger

By encapsulating nanoscale particles of goethite (α-FeO(OH)), hydrous ceric oxide (CeO2·H2O, HCO) and silver nanoparticles (AgNPs) in the pores of polystyrene anion exchanger D201, a novel nanocomposite FeO(OH)-HCO-Ag-D201 was prepared for the effective removal of arsenic from water. The isotherm study shows that FeO(OH)-HCO-Ag-D201 has excellent adsorption performance for As(III) and As(V), with an increased adsorption capacity of As(III) to 40.12 mg/g compared to that of 22.03 mg/g by the composite adsorbent without AgNPs (FeO(OH)-HCO-D201). The adsorption kinetics data showed that the sorption rate of FeO(OH)-HCO-Ag-D201 for As(III) is less than that for As(V), and the adsorption of As(III) and As(V) were consistent with the pseudo-second-order model and the pseudo-first-order model, respectively. Neutral or basic conditions are favored for the adsorption of As(III/V) by FeO(OH)-HCO-Ag-D201. Compared with nitrate/chloride/bicarbonate, sulfate/silicate/phosphate showed more remarkable inhibition of arsenic removal by FeO(OH)-HCO-Ag-D201, whereas natural organic matter showed no interference to the arsenic removal. The As(V) adsorption involved different interactions such as electrostatic attraction and surface complexation, while the adsorption of As(III) involved the part oxidization of As(III) to As(V) and the simultaneous adsorption of As(III) and As(V). In addition to the Ce(IV) in CeO2·H2O acted as an oxidant, the synergistic effect of α-FeO(OH) and AgNPs also contributed to the oxidization of As(III) to As(V). Moreover, the reusable property suggested that this FeO(OH)-HCO-Ag-D201 nanocomposite has great potential for arsenic-contaminated water purification.

Enhanced mechanical properties of thermo-mechanically affected zone of friction-stir welded AZ61 magnesium alloy joint

Friction-stir welded (FSW) magnesium alloy joints frequently fracture at thermo-mechanically affected zone (TMAZ), and the joints exhibit unsatisfactory welding efficiency and ductility. The TMAZ is considered as the weakest region of the entire joint. Enhance the mechanical properties of TMAZ can improve the performance of the welded joint. In this work, subsequent aging treatment and pre-strain of 3% along the weld seam were conducted on the FSW AZ61 magnesium alloy joint. The microstructure of the TMAZ is characterized by abundant nanoscale second phase particles and {10–12} twins. The reduced basal texture intensity decreased the anisotropy of plastic deformation. The welded joint showed a good synergic of welding efficiency (96%) and ductility (20%). The enhanced strength is attributed to the blocking effect of nanoscale particles and grain/twin boundaries to dislocation movement. The increasing of twin boundaries is the main reason for the improvement of work hardening ability and ductility during tensile deformation. This work demonstrated that introducing {10–12} twins and nanoscale particles into TMAZ is an effective way to improve the balance of strength and ductility of the welded joint due to the synergistic effect of multiple strengthening and toughening mechanisms.

Optimizing Wound Healing: Examining the Influence of Biopolymers Through a Comprehensive Review of Nanohydrogel-Embedded Nanoparticles in Advancing Regenerative Medicine.

Nanohydrogel wound healing refers to the use of nanotechnology-based hydrogel materials to promote the healing of wounds. Hydrogel dressings are made up of a three-dimensional network of hydrophilic polymers that can absorb and retain large amounts of water or other fluids. Nanohydrogels take this concept further by incorporating nanoscale particles or structures into the hydrogel matrix. These nanoparticles can be made of various materials, such as silver, zinc oxide, or nanoparticles derived from natural substances like chitosan. The inclusion of nanoparticles can provide additional properties and benefits to the hydrogel dressings. Nanohydrogels can be designed to release bioactive substances, such as growth factors or drugs, in a controlled manner. This allows for targeted delivery of therapeutics to the wound site, promoting healing and reducing inflammation. Nanoparticles can reinforce the structure of hydrogels, improving their mechanical strength and stability. Nanohydrogels often incorporate antimicrobial nanoparticles, such as silver or zinc oxide. These nanoparticles have shown effective antimicrobial activity against a wide range of bacteria, fungi, and other pathogens. By incorporating them into hydrogel dressings, nanohydrogels can help prevent or reduce the risk of infection in wounds. Nanohydrogels can be designed to encapsulate and release bioactive substances, such as growth factors, peptides, or drugs, in a controlled and sustained manner. This targeted delivery of therapeutic agents promotes wound healing by facilitating cell proliferation, reducing inflammation, and supporting tissue regeneration. The unique properties of nanohydrogels, including their ability to maintain a moist environment and deliver bioactive agents, can help accelerate the wound healing process. By creating an optimal environment for cell growth and tissue repair, nanohydrogels can promote faster and more efficient healing of wounds.

Enhanced size-dependent efficiency of removal of ultrafine particles: New solution of two-stage electrostatic precipitator with thermophoresis

Two-stage electrostatic precipitators (ESPs) are effective at removing ultrafine particles (UFPs) from gases; however, they fall short in capturing particles with diameters of less than 100 nm. In this study, an effective solution for removal of particles smaller than 300 nm was proposed. Our self-designed system combines a two-stage ESP with thermophoresis. We employed a combination of experimental and numerical simulation methods to examine the effects of temperature and thermophoresis on particle removal efficiency influenced by electrostatic forces. In our experiments, particle removal efficiency was positively correlated with gas temperature up to 75 °C, beyond which removal efficiency was no longer correlated with temperature. The findings also indicate that the introduction of thermophoresis improves particle removal efficiency, with the maximum increase approaching 8 %. However, this effect only occurs for particles smaller than 50 nm. The increase in the length of the thermophoresis segment and the decrease in inlet gas flow rate both enhance particle removal efficiency due to thermophoresis. Numerical simulations confirmed the experimental finding that nanoscale particles are more easily captured at higher temperatures. The simulations also revealed that the primary reasons for the enhanced removal efficiency are twofold: greater electric field strength and higher particle charge resulting from a higher temperature.

A Review Concept on Polymer Micelles

Polymeric micelles present a viable approach for research on drug delivery and targeting. Compared to surfactant micelles, polymeric micelles are nanoscale colloid particles that self-assemble from amphiphilic block co-polymers. Their inner core has the ability to solubilize significant amounts of hydrophobic substances. This article has covered a number of topics regarding polymeric micelles, including their fundamentals, which include their size, shape, chemistry, general characteristics, structure analysis, and mechanism of production. The many kinds of polymeric micelles were also emphasised.

Effective Prevention of Palladium Metal Particles Sintering by Histidine Stabilization on Silica Catalyst Support

AbstractA robust method for enhancing the dispersion and stabilization of small metal nanoparticles in heterogeneous catalysts is developed. It involves in situ complexation of palladium(II) by histidine, in water, prior to impregnation in fumed silica. TEM images show that the histidine facilitates dispersion of the Pd(II) into finer nanoscale particles (≈2 nm) uniformly distributed on the support, rather than the large clusters (≈5 nm) seen in the absence of histidine. After hydrogen reduction, assessments using CO chemisorption and propylene hydrogenation indicate that the coordinated histidine might obscure the active sites on the Pd particles. However, as histidine decomposes between 220 and 300 °C in air, these materials are treated at 225 °C in air for 48 h. Afterwards the Pd(II) particles remain the same size, but after hydrogen reduction, there is a 2.4‐fold increase in CO gas adsorption, indicative of an expanded Pd surface area. Furthermore, superior catalyst stability (activity >200 h) is observed during propylene hydrogenation at 250 °C. This is consistent with histidine use having generated widely spaced, uniformly small, Pd nanoparticles on the silica support which is expected to help prevent agglomeration (sintering) during catalysis. This is a convenient low‐cost strategy for reducing metal content, preventing sintering and optimizing catalyst performance.

The Prospect of Biomimetic Immune Cell Membrane-Coated Nanomedicines for Treatment of Serious Bacterial Infections and Sepsis.

Invasive bacterial infections and sepsis are persistent global health concerns, complicated further by the escalating threat of antibiotic resistance. Over the past 40 years, collaborative endeavors to improve the diagnosis and critical care of septic patients have improved outcomes, yet grappling with the intricate immune dysfunction underlying the septic condition remains a formidable challenge. Anti-inflammatory interventions that exhibited promise in murine models failed to manifest consistent survival benefits in clinical studies through recent decades. Novel therapeutic approaches that target bacterial virulence factors, for example with monoclonal antibodies, aim to thwart pathogen-driven damage and restore an advantage to the immune system. A pioneering technology addressing this challenge is biomimetic nanoparticles-a therapeutic platform featuring nanoscale particles enveloped in natural cell membranes. Borne from the quest for a durable drug delivery system, the original red blood cell-coated nanoparticles showcased a broad capacity to absorb bacterial and environmental toxins from serum. Tailoring the membrane coating to immune cell sources imparts unique characteristics to the nanoparticles suitable for broader application in infectious disease. Their capacity to bind both inflammatory signals and virulence factors assembles the most promising sepsis therapies into a singular, pathogen-agnostic therapeutic. This review explores the ongoing work on immune cell-coated nanoparticle therapeutics for infection and sepsis. SIGNIFICANCE STATEMENT: Invasive bacterial infections and sepsis are a major global health problem made worse by expanding antibiotic resistance, meaning better treatment options are urgently needed. Biomimetic cell-membrane-coated nanoparticles are an innovative therapeutic platform that deploys a multifaceted mechanism to action to neutralize microbial virulence factors, capture endotoxins, and bind excessive host proinflammatory cytokines, seeking to reduce host tissue injury, aid in microbial clearance, and improve patient outcomes.

The influence of zinc oxide-silicate composites on the aging resistance of asphalt

Asphalt binder is susceptible to aging from heat, air and sunlight exposure during service, leading to pavement distresses. This study aimed to improve the aging resistance of asphalt using zinc oxide-silicate (ZOS) composites. ZOS containing 2–8 wt% ZnO were synthesized via a one-step sol-gel method and incorporated into an unmodified 70/100 penetration grade asphalt binder. The rheological properties and aging characteristics were evaluated before and after rolling thin film oven and pressure aging vessel protocols. Dynamic shear rheometry showed increased complex modulus and decreased phase angle for ZOS-modified binders, indicating improved rutting resistance. Aging indices revealed the 6% ZOS composite had the least susceptibility to oxidative aging. FTIR analysis confirmed the formation of carbonyl and sulfoxide functional groups during aging, which were mitigated by ZOS addition. Scanning electron microscopy visualized nano-scaled ZnO particles dispersed within the silica matrix and asphalt binder. The ZOS composites delayed the aging rate through physicochemical interactions between ZnO and the asphalt medium. An optimum ZOS dosage of 4–6% was found to enhance the anti-aging properties. The renewable silica-supported ZnO composites show potential as cost-effective modifiers for improving asphalt durability.

Wmic-GMTS and Wmic-GMERR criteria for micron-scale crack propagation in red-bed soft rocks under hydraulic action

Micron-scale crack propagation in red-bed soft rocks under hydraulic action is a common cause of engineering disasters due to damage to the hard rock–soft rock–water interface. Previous studies have not provided a theoretical analysis of the length, inclination angle, and propagation angle of micron-scale cracks, nor have they established appropriate criteria to describe the crack propagation process. The propagation mechanism of micron-scale cracks in red-bed soft rocks under hydraulic action is not yet fully understood, which makes it challenging to prevent engineering disasters in these types of rocks. To address this issue, we have used the existing generalized maximum tangential stress (GMTS) and generalized maximum energy release rate (GMERR) criteria as the basis and introduced parameters related to micron-scale crack propagation and water action. The GMTS and GMERR criteria for micron-scale crack propagation in red-bed soft rocks under hydraulic action (abbreviated as the Wmic-GMTS and Wmic-GMERR criteria, respectively) were established to evaluate micron-scale crack propagation in red-bed soft rocks under hydraulic action. The influence of the parameters was also described. The process of micron-scale crack propagation under hydraulic action was monitored using uniaxial compression tests (UCTs) based on digital image correlation (DIC) technology. The study analyzed the length, propagation and inclination angles, and mechanical parameters of micron-scale crack propagation to confirm the reliability of the established criteria. The findings suggest that the Wmic-GMTS and Wmic-GMERR criteria are effective in describing the micron-scale crack propagation in red-bed soft rocks under hydraulic action. This study discusses the mechanism of micron-scale crack propagation and its effect on engineering disasters under hydraulic action. It covers topics such as the internal-external weakening of nano-scale particles, lateral propagation of micron-scale cracks, weakening of the mechanical properties of millimeter-scale soft rocks, and resulting interface damage at the engineering scale. The study provides a theoretical basis for the mechanism of disasters in red-bed soft-rock engineering under hydraulic action.

Nano zero-valent iron/montmorillonite composite for the removal of Cr(VI) from aqueous solutions: Characterization, performance, and mechanistic insights

Infiltration of hexavalent chromium (Cr(VI)) into the human body poses significant health risks, including the risk of developing cancer and increased mortality rates. The discharge of chromium-contaminated wastewater from industrial processes exacerbates environmental pollution, highlighting the necessity for efficient, cost-effective, and environmentally friendly treatment methods. In recent years, there has been a growing emphasis on the application of nanoscale zero-valent iron particles (NZVI) for mitigating Cr(VI) water pollution. In the present study, NZVI was synthesized using a liquid-phase reduction method employing sodium borohydride (NaBH4), and natural montmorillonite (Mt) was incorporated as a carrier, resulting in the creation of NZVI/Mt., a composite material. Characterization of this composite was performed using scanning electron microscopy (SEM), Transmission Electron Microscope (TEM), Specific surface area and pore size (BET), X-ray diffraction (XRD), and Fourier-transform infrared (FT-IR) techniques. The investigation encompassed an exploration of the influence of initial pollutant pH levels, adsorbent dosages, and initial pollutant concentrations on the adsorption process. The research findings indicate that, at an initial pH of 4.0, NZVI/Mt. achieves a removal efficiency of 92.41% for a Cr(VI) solution with an initial concentration of 40 mg/L. The NZVI/Mt. composite adheres to both a pseudo-second-order kinetic model and the Langmuir isotherm model, showcasing a significant maximum adsorption capacity of 67.75 mg/g for Cr(VI). Furthermore, thermodynamic analysis revealed an exothermic nature of the adsorption process. This experimental approach effectively resolved issues related to NZVI particle agglomeration, offering a simplified, cost-effective, and environmentally friendly preparation method. Consequently, the NZVI/Mt. composite material demonstrates effective treatment of Cr(VI) mildly contaminated wastewater.

Vapor‐Phase Synthesis of Poly(para‐xylylene): From Coatings to Porous and Hierarchical Materials

AbstractPoly(para‐xylylene) (PPX) is a robust and biocompatible coating material that is widely used in various applications, including electronics, aerospace and defense materials, automotive materials, and biomaterials. In this progress report, recent developments in PPX technology ranging from the advancement of physical chemistry properties and structural properties for device integration to the transformation of 3D monolith materials of PPX with controls in outer and inner structures at the micro‐ and nanometer scales are highlighted. Based on emerging chemistry studies on [2.2]paracyclophanes, which are primarily used precursors to synthesize PPX via vapor deposition polymerization, functionalization, and the creation of a wide variety of functional PPX derivatives are demonstrated without resistance. Widely used as an interface coating material, PPX is processed to form integrated structural materials and has already been found to be useful in the market as part of electronic and medical implant products. Using a newly innovated transformation to fabricate PPX through templates (metal‐organic frameworks, liquid crystal, ice crystal), 3D monoliths, nanoscale particles, hierarchical and gradient interior structures, and dynamically transformable shapes at the nanoscale are demonstrated. A vast landscape of novel applications and device products is expected based on the already established R&D and market maturity of PPX.

Wear Behavior of Epoxy Resin Reinforced with Ceramic Nano- and Microparticles.

Cavitation erosion poses a significant challenge in fluid systems like hydraulic turbines and ship propellers due to pulsed pressure from collapsing vapor bubbles. To combat this, various materials and surface engineering methods are employed. In this study, nano and micro scale particles of silicon carbide (SiC) or boron carbide (B4C) were incorporated as reinforcement at 6% and 12% ratios, owing to their exceptional resistance to abrasive wear and high hardness. Microparticles were incorporated to assess the damage incurred during the tests in comparison to nanoparticles. Wear tests were conducted on both bulk samples and coated aluminum sheets with a 1mm of composite. Additionally, cavitation tests were performed on coated aluminum tips until stability of mass loss was achieved. The results indicated a distinct wear behavior between the coatings and the bulk samples. Overall, wear tended to be higher for the coated samples with nanocomposites than bulk, except for the nano-composite material containing 12% SiC and pure resin. With the coatings, higher percentages of nanometric particles correlated with increased wear. The coefficient of friction remained within the range of 0.4 to 0.5 for the coatings. Regarding the accumulated erosion in the cavitation tests for 100 min, it was observed that for all nanocomposite materials, it was lower than in pure resin. Particularly, the composite with 6% B4C was slightly lower than the rest. In addition, the erosion rate was also lower for the composites.

Multiphase strengthening mechanism of Cu-Y2O3/W composites prepared by mechanical alloying

To prepare high-performance copper-based composites, Y2O3/W multiphase reinforced copper-based composites were synthesized through mechanical alloying and spark plasma sintering, and the mole ratio of W and Y2O3 was explored. It is found that the incorporation of W inhibited the growth of copper particle during ball milling, and facilitated the refinement of Y2O3. Compared to conditions without W addition, the Y2O3 particle diameter reduced from 97.96 nm to 33.4 nm when same mole W was added. Furthermore, copper grains were refined, resulting in a higher tensile strength of 305 MPa and elongation of 15.6 %. At 400 °C, the 5:5 sample exhibited a higher thermal conductivity of 299 W/(m·K). Nano-scale particles were uniformly distributed within the copper matrix, and the interaction between W and Y2O3 inhibited nanoparticle coarsening, leading to the formation of a more stable Y2WO6 phase during sintering, which is also better for the purification of the copper matrix.

Gold Migration and Precipitation as Collaurum in Orogenic Gold Deposits: Constrains from Microscopic Gold Particles Observed in the Alteration Zone in Shanggong Gold Ore, Henan, China

Aqueous complexation has long been considered the only viable means of transporting gold to depositional sites in hydrothermal ore-forming systems. Here, we present direct evidence supporting an alternative hypothesis, namely, the transport of gold as colloidal particles. We observed nano-scale gold particles adsorbed on halloysite and micro-scale gold particles in altered rocks by TEM and SEM in the Shanggong orogenic gold deposit. Based on this evidence, we propose a feasible model for the origin of microscopic gold particles in alteration zones. In the early stage of ore-forming fluid, gold may migrate in the form of collaurum, which is maintained by supercritical CO2 and colloidal silica. Low salinity and high pressure are conducive to the stable migration of colloidal gold. When the physicochemical conditions change, some collaurum is precipitated and adsorbed by the clay minerals produced by hydrothermal alteration, and some collaurum undergoes growth and evolves into micro-submicrometer-sized gold particles. This study highlighted the significance of collaurum in the formation of orogenic gold deposits.

Agglomeration behavior of carbon-supported platinum nanoparticles in catalyst ink: modeling and experimental investigation

Within catalyst inks, the agglomeration of carbon-supported Pt nanoparticles (Pt/C NPs) stands out as a primary destabilizing factor. This study simulates the agglomeration process of particles under varying ionic strengths (ISs), employing the Brownian motion of Pt/C NPs and inter-particle forces. The energy barriers (EBs) within particles govern particle interactions, subsequently translating into the adhesive efficiency of particle collisions (α). By modulating the ISs in Ink-P (IS = 0.00182), Ink-01 (IS = 0.01), and Ink-001 (IS = 0.001), the Zeta potential and EBs are diminished, thereby increasing α. Structural parameters of agglomerates during the agglomeration process, such as fractal dimension (df) and porosity, are computationally assessed using Matlab. The simulated df for Ink-P, Ink-001, and Ink-01 are 1.82, 1.62, and 1.54, respectively, while the experimentally measured df are 1.92–1.95, 1.67–1.7, and 1.56–1.59, confirming the effectiveness of the simulation method. High α led to isotropic growth of agglomerates, resulting in higher df. Increased IS causes compression of the electric double layer and higher α, ultimately leading to rapid destabilization of the ink. This method not only enhances comprehension of nanoscale particle agglomeration, explaining variations in ink stability and agglomerate structures, but also broadens its applicability to diverse nanoparticle dispersion systems.

New Schiff's base derivative and their nano‐sized Cr (III), Fe (III), Ru (III), and Ir (III) complexes: Preparation, DFT, characterization, bio‐catalytic, DNA interactions, cytotoxicity, and docking studies

Nano‐sized trivalent metal complexes of Cr (III), Fe (III), Ru (III), and Ir (III) were synthesized and characterized of the form [M (FMAVIEP)Cl2] where FMAVIEP = ligand (C14H11N2O2) and M = Cr (III), Fe (III), Ru (III), and Ir (III). Several spectral techniques studies were used to assess our trivalent metal complexes. The trivalent metal complexes' XRD results revealed sharp and intense diffraction peaks, signifying their crystalline properties at nanoscale particle size. Further evidence was obtained from images captured through techniques such as SEM, TEM, energy‐dispersive X‐ray, and AFM. These images confirmed the homogeneous distribution of the trivalent metal complexes over the surface of the complex. DFT studies were used to study the nano‐sized metal (III) complexes via the DFT\B3LYP computational approach, employing a 6–311G* correlation consistent basis set. The energy gap of synthesized complexes was inspected. The obtained data exhibited a strong correlation with the experimental ones, implying the bio‐efficiency of the Ru (III) complex. The absorption measurements for the nano‐sized complexes' interaction with CT‐DNA signify that nano‐sized metal (III) complexes bind through an intercalation mechanism. This conclusion is supported by the observed intrinsic binding constant (Kb) 3.33 × 105–5.84 × 105 M−1.

Bionanofactory for green synthesis of collagen nanoparticles, characterization, optimization, in-vitro and in-vivo anticancer activities

Collagen nanoparticles (collagen-NPs) are promising biological polymer nanoparticles due to their exceptional biodegradability and biocompatibility. Collagen-NPs were bio-fabricated from pure marine collagen using the cell-free supernatant of a newly isolated strain, Streptomyces sp. strain NEAA-3. Streptomyces sp. strain NEAA-3 was identified as Streptomyces plicatus strain NEAA-3 based on its cultural, morphological, physiological properties and 16S rRNA sequence analysis. The sequence data has been deposited under accession number OR501412.1 in the GenBank database. The face-centered central composite design (FCCD) was used to improve collagen-NPs biosynthesis. The maximum yield of collagen-NPs was 9.33 mg/mL with a collagen concentration of 10 mg/mL, an initial pH of 7, an incubation time of 72 h, and a temperature of 35 °C. Using the desirability function approach, the collagen-NPs biosynthesis obtained after FCCD optimization (9.53 mg/mL) was 3.92 times more than the collagen-NPs biosynthesis obtained before optimization process (2.43 mg/mL). The TEM analysis of collagen-NPs revealed hollow sphere nanoscale particles with an average diameter of 33.15 ± 10.02 nm. FTIR spectra confirmed the functional groups of the collagen, collagen-NPs and the cell-free supernatant that are essential for the efficient capping of collagen-NPs. The biosynthesized collagen-NPs exhibited antioxidant activity and anticancer activity against HeP-G2, MCF-7 and HCT116 cell lines. Collagen-NPs assessed as an effective drug loading carrier with methotrexate (MTX), a chemotherapeutic agent. The TEM analysis revealed that the average size of MTX-loaded collagen-NPs was 35.4 ± 8.9 nm. The percentages of drug loading (DL%) and encapsulation efficiency (EE%) were respectively 22.67 and 45.81%.

On the mechanisms of cardiotoxic action of various nanoparticles in experimental studies in vivo and in vitro

Nanoparticles are the main product of artificial technologies, and also accompany production processes in various industries. The main routes of exposure to nanoparticles are through the respiratory tract, skin and orally; therefore, most toxicological studies have focused on the lungs, liver and skin. Nanoscale particles easily penetrate the alveolar-capillary barrier and enter the bloodstream of the body. Thus, they can reach various organs, accumulate, cause toxicity, and the heart is one of the target organs.
 The study aims to search and systematize the literature data on the mechanisms of cardiotoxic action of nanoparticles of various chemical nature (elemental, elementoxide).
 The researchers conducted a literature review as part of a study of the cardiotoxic effect of nanoparticles on the body. The review is based on modern original research. When searching for literary sources, the authors used the following information databases: PubMed, Google Scholar, CyberLeninka Scientific Electronic Library, Russian Scientific Electronic Library eLibrary.Ru. In total, there were 37 original articles in the review, including 35 foreign ones, and 15 — no older than 5 years. The development of oxidative stress and an inflammatory reaction leads to the formation of cardiotoxicity of nanomaterials, which subsequently leads to necrosis and apoptosis of cells.
 Indicators of oxidative damage to lipids and DNA molecules indicate that the tissues of the heart and lungs suffer from oxidative stress not only as a result of an increase in the formation of reactive oxygen species, but also due to a malfunction of antioxidant mechanisms caused by exposure to nanoparticles.
 Studies using endothelial cells have shown that exposure to metal and metal oxide nanoparticles can promote the release of cytokines, the expression of adhesion molecules and monocyte adhesion, which are key events associated with the development of cardiovascular diseases.
 These results, combined with other in vitro data, suggest that direct contact of the cardiovascular system with metal-based nanoparticles may cause cardiovascular toxicity associated with inflammatory reactions, oxidative stress, autophagy dysfunction and endoplasmic reticulum stress. Oxidative stress induced by nanoparticles leads to apoptosis and inflammatory reactions in cardiomyocytes, as well as disrupts the integrity of mitochondrial membranes and cell organelles, leading to various heart pathologies. One of the main mechanisms of toxicity of nanoparticles of different chemical nature is oxidative stress.

Study on friction reduction performance of granular flow lubrication during the milling of Inconel 718 superalloy

PurposeThe purpose of this study is to reveal the friction reduction performance and mechanism of granular flow lubrication during the milling of difficult-to-machining materials and provide a high-performance lubrication method for the precision cutting of nickel-based alloys.Design/methodology/approachThe milling tests for Inconel 718 superalloy under dry cutting, flood lubrication and granular flow lubrication were carried out, and the milling force and machined surface quality were used to evaluate their friction reduction effect. Furthermore, based on the energy dispersive spectrometer (EDS) spectrums and the topographical features of machined surface, the lubrication mechanism of different granular mediums was explored during granular flow lubrication.FindingsCompared with flood lubrication, the granular flow lubrication had a significant force reduction effect, and the maximum milling force was reduced by about 30%. At the same time, the granular flow lubrication was more conducive to reducing the tool trace size, repressing surface damage and thus achieving better surface quality. The soft particles had better friction reduction performance than the hard particles with the same particle size, and the friction reduction performance of nanoscale hard particles was superior to that of microscale hard particles. The friction reduction mechanism of MoS2 and WS2 soft particles is the mending effect and adsorption film effect, whereas that of SiO2 and Al2O3 hard particles is mainly manifested as the rolling and polishing effect.Originality/valueGranular flow lubrication was applied in the precision milling of Inconel 718 superalloy, and a comparative study was conducted on the friction reduction performance of soft particles (MoS2, WS2) and hard particles (SiO2, Al2O3). Based on the EDS spectrums and topographical features of machined surface, the friction reduction mechanism of soft and hard particles was explored.