Diameter Of Nanoparticles Research Articles

Antimicrobial Activities of Polyethylene Terephthalate-Waste-Derived Nanofibrous Membranes Decorated with Green Synthesized Ag Nanoparticles.

Thermoplastic polymers are one of the synthetic materials produced with high tonnage in the world and are so omnipresent in industries and everyday life. One of the most important polymeric wastes is polyethylene terephthalate (PET), and the disposal of used PET bottles is an unsolved environmental problem, and many efforts have been made to find practical solutions to solve it. In this present work, nanofibrous membranes were produced from waste PET bottles using the electrospinning process. The surface of membranes was modified using NaOH and then decorated with green synthesized Ag nanoparticles (10 ± 2 nm) using an in situ chemical reduction method. The morphology, size, and diameter of the Ag nanoparticles decorating the nanofibers were characterized through transmission electron microscopy (TEM), a field emission scanning electron microscope (FESEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and UV-visible spectroscopy techniques. Finally, the antimicrobial activity of the nanofibrous membranes was tested against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus using disc diffusion and colony-forming count methods. The growth of bacteria was not affected by the pure nanofibrous membranes, while the Ag-decorated samples showed inhibition zones of 17 ± 1, 16 ± 1, and 14 ± 1 mm for Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus, respectively. The planktonic culture results of Pseudomonas aeruginosa showed that the membranes had a relatively low inhibitory effect on its growth. The obtained results showed that Pseudomonas aeruginosa has a relatively low ability to form biofilms on the nanostructured membranes too. A good agreement was observed between the data of biofilm formation and the planktonic cultures of bacteria. The plastic-waste-derived PET/Ag nanocomposite membranes can be used for wound dressings, air filters, and water purification applications.

CO2 absorption enhancement in low transition temperature mixtures-based nanofluids: Experiments and modeling

The enhancement of gas–liquid mass transfer in the CO2 absorption process by Low Transition Temperature Mixtures (LTTMs) based nanofluids was investigated. The effects of loading and size of TiO2 nanoparticles on the CO2 absorption rate were studied experimentally. The absorption rate was found to be improved significantly after adding nanoparticles. The maximum enhancement factor of 1.35 was observed when using nanoparticles with a particle size of 10 nm and a concentration of 0.6 kg/m3. The maximum absorption enhancement factor and mass transfer coefficient were observed when the loading of nanoparticles increased, hence there was an optimal concentration of TiO2 nanoparticles in the CO2 absorption process. For the size of nanoparticles, the CO2 absorption rate was higher when the diameter of nanoparticles decreased. Furthermore, a three-dimensional unsteady mathematical model of gas–liquid mass transfer, which was based on the mechanisms of grazing effect and hydrodynamic effect in the gas–liquid boundary layer, was developed to describe the CO2 absorption enhancement. The model predictions were well consistent with the experimental results, with a maximum deviation of less than 5%, which proved the reliability of the model. Finally, Molecular dynamics simulations were conducted on the absorbent-CO2 system. The results showed that the addition of TiO2 nanoparticles led to a reduction in the simulation box size at the same simulation time, but it did not significantly alter the interaction between LTTMs and CO2. Therefore, it can be inferred that TiO2 nanoparticles enhance CO2 absorption capacity by modifying the mass transfer rate. Through the aforementioned study, this paper explores the experimental and mechanistic aspects of nanoparticle-enhanced absorption of CO2 in LTTMs systems. The research demonstrates the feasibility of nanoparticle-enhanced absorption of CO2 in LTTMs solvents, providing insights into studying nanoparticle-enhanced gas–liquid mass transfer and offering a new research approach for CO2 capture.

Room Temperature Ion Beam Synthesis of Ultra-Fine Molybdenum Carbide Nanoparticles: Toward a Scalable Fabrication Route for Earth-Abundant Electrodes.

Molybdenum carbides are promising low-cost electrocatalysts for electrolyzers, fuel cells, and batteries. However, synthesis of ultrafine, phase-pure carbide nanoparticles (diameter<5nm) with large surface areas remains challenging due to uncontrollable agglomeration that occurs during traditional high temperature syntheses. This work presents a scalable, physical approach to synthesize molybdenum carbide nanoparticles at room temperature by ion implantation. By tuning the implantation conditions, various molybdenum carbide phases, stoichiometries, and nanoparticle sizes can be accessed. For instance, molybdenum ion implantation into glassy carbon at 30keV energy and to a fluence of 9×1016 atcm-2 yields a surface η-Mo3C2 with a particle diameter of (10±1)nm. Molybdenum implantation into glassy carbon at 60keV to a fluence of 6×1016 atcm-2 yields a buried layer of ultrafine γ'-MoC/η-MoC nanoparticles. Carbon ion implantation at 20keV into a molybdenum thin film produces a 40nm thick layer primarily composed of β-Mo2C. The formation of nanoparticles in each molybdenum carbide phase is explained based on the Mo-C phase diagram and Monte-Carlo simulations of ion-solid interactions invoking the thermal spike model. The approaches presented are widely applicable for synthesis of other transition metal carbide nanoparticles as well.

Towards Digital Twins of Plasmonic Sensors: Constructing the Complex Numerical Model of a Plasmonic Sensor Based on Hexagonally Arranged Gold Nanoparticles.

In this work, we aim to design the digital twin of a plasmonic sensor based on hexagonally arranged ellipsoidal gold nanoparticles fixed to a glass substrate. Based on electron microscopy images of three experimentally realized nanoparticle arrangement types, we constructed numerical models in environments based on finite element method (FEM) and boundary element method (BEM), namely COMSOL Multiphysics for FEM and the MNPBEM Matlab Toolbox for BEM. Models with nonperiodic and periodic boundary conditions with different unit cells were constructed to study the plasmonic behavior of both the single ellipsoidal particles and the hexagonal nanoparticle arrangements. The effect of the geometrical parameters, namely the interparticle distance, the nanoparticle diameter and thickness, on the resulting LSPR peak positions and bulk refractive index sensitivities were studied in detail, also taking into account the effect of the SiO2 substrate (pillars) under the ellipsoidal particles. We have demonstrated that by optimizing the models, the LSPR peak positions (and sensitivities) can match the experimentally measured values within 1 nm (nm/RIU) precision. The comparison of simulation conditions and the detailed discussion of the effect of the geometrical parameters and used gold dielectric functions on the obtained sensitivities can be very beneficial for the optimization of plasmonic sensor constructions through numerical simulations.

Mechanism and antibacterial synergies of poly(Dabco-BBAC) nanoparticles against multi-drug resistant Pseudomonas aeruginosa isolates from human burns

Multi-drug resistant bacteria are a major problem in the treatment of infectious diseases, such as pneumonia, meningitis, or even coronavirus disease 2019 (COVID-19). Cationic nanopolymers are a new type of antimicrobial agent with high efficiency. We synthesized and characterized cationic polymer based on 1,4-diazabicyclo [2.2.2] octane (DABCO) and Bis (bromoacetyl)cystamine (BBAC), named poly (DABCO-BBAC) nanoparticles(NPs), and produced 150 nm diameter NPs. The antibacterial activity of poly (DABCO-BBAC) against eight multi drug resistant (MDR) Pseudomonas aeruginosa isolates from human burns, its possible synergistic effect with gentamicin, and the mechanism of action were examined. Poly(DABCO-BBAC) could effectively inhibit and kill bacterial strains at a very low concentration calculated by minimum inhibitory concentration (MIC) assay. Nevertheless, its synergism index with gentamicin showed an indifferent effect. Moreover, transmission electron microscopy and lipid peroxidation assays showed that poly (DABCO-BBAC) distorted and damaged the bacterial cell wall. These results suggest that the poly (DABCO-BBAC) could be an effective antibacterial agent for MDR clinical pathogens.

Experimental analysis of heat exchanger using perforated conical rings, twisted tape inserts and CuO/H2O nanofluids

This research paper presents an experimental analysis on a heat exchanger tube using a newly designed perforated conical ring combined with twisted tape as inserts. The investigation analyzes various geometric and flow parameters in the experimental setup, including a wide range of Reynolds numbers, varying from 6000 to 30000, nanoparticle volume concentration (φnp) of 0.25-1.0%, the ratio of inlet flow dia to inner print dia of the ring (DIR/DBR) of 1.33-2.33, ring pitch ratio (RP/ DED) of 1.41-2.51, twist ratio (TL/ WT) of 3.33-4.38, with fixed values for other parameters: relative ring height ((DED/ WR) of 2.33 and nanoparticle diameter (dnp) of 30 nm. The optimal result of the thermal-hydraulic performance parameter (ηTT) is 1.45 at DIR/DBR = 1.83, TL/ WT = 3.50 and RP/ DED = 1.76. For the CuO/H2O nanofluids flow heat exchanger tube with perforated conical rings, empirical correlations were developed for the Nusselt number and the friction factor. These correlations were established with a range of 9.0% and 8.0%, respectively.

Preparation and characterization of solid lipid nanoparticles incorporating bioactive coumarin analogues as photosensitizing agents

Daphnetin (7,8-dihydroxy-coumarin, DAPH) is a naturally occurring coumarin presenting a wide array of biological activities. In the present study, daphnetin and its novel synthetic analogue 7,8-dihydroxy-4-methyl-3-(4-hydroxyphenyl)-coumarin (DHC) were encapsulated in solid lipid nanoparticles (SLNs) with Encapsulation Efficiency values of 80% and 40%, respectively. Nanoparticles of an average hydrodynamic diameter of approximately 250 nm were formed, showing a good stability in aqueous dispersion (polydispersity index 0.3–0.4), as determined by Dynamic Light Scattering (DLS). The SLNs were also characterized using Fourier Transform-Infrared (FT-IR) spectroscopy and Thermogravimetric Analysis (TGA). TEM images of the blank-SLNs indicated a spherical morphology and a size of 20–50 nm. The release studies of the coumarin analogues indicated a non-Fickian diffusion mechanism, while the release profiles better fitted on the Higuchi kinetic model. Moreover, the coumarin analogues and their SLNs were examined for their antioxidant activity using DPPH and anti-lipid peroxidation assays, exhibiting stronger antioxidant activity when encapsulated than in their free form. The coumarin derivatives and their SLNs were examined for their photodynamic therapy (PDT) efficacy against the human squamous carcinoma A431 cell line, with DHC coumarin both in its free and encapsulated form exhibiting significant PDT activity, reducing the cell viability to 11% after irradiation with a fluence rate of 2.16 J/cm2. Finally, the intracellular localization studies indicated the enhanced cellular uptake of the coumarin analogues when loaded in the SLNs.

Gold Nanoparticles AuNP Decorated on Fused Graphene-like Materials for Application in a Hydrogen Generation.

The search for a sustainable, alternative fuel source to replace fossil fuels has led to an increased interest in hydrogen fuel. This combustible gas is not only clean-burning but can readily be produced via the hydrolysis of sodium borohydride. The main drawback of this reaction is that the reaction occurs relatively slowly and requires a catalyst to improve efficiency. This study explored a novel composite material made by combining gold nanoparticles and fused graphene-like materials (AuFGLM) as a catalyst for generating hydrogen via sodium borohydride. The novel fused graphene-like material (FGLM) was made with a sustainable dextrose solution and by using a pressure-processing method. Imaging techniques showed that FGLM appears to be an effective support template for nanoparticles. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Raman spectroscopy were used to characterize and determine the size, shape, and structure of nanoparticles and composites. The TEM study characterized the fused carbon backbone as it began to take on a rounder shape. The TEM images also revealed that the average diameter of the gold nanoparticle was roughly 23 nm. The FTIR study confirmed O-H, C-C, and C=O as functional groups in the materials. The EDS analysis showed that the composite contained approximately 6.3% gold by weight. The crystal structures of FGLM and AuFGLM were identified via P-XRD analysis. Various reaction conditions were used to test the catalytic ability of AuFGLM, including various solution pHs, temperatures, and doses of NaBH4. It was observed that optimal reaction conditions included high temperature, an acidic solution pH, and a higher dose of NaBH4. The activation energy of the reaction was determined to be 45.5 kJ mol-1, and it was found that the catalyst could be used multiple times in a row with an increased volume of hydrogen produced in ensuing trials. The activation energy of this novel catalyst is competitive compared to similar catalysts and its ability to produce hydrogen over multiple uses makes the material an exciting choice for catalyzing the hydrolysis of NaBH4 for use as a hydrogen fuel source.

Calcium Sulfate Nanoparticles in Surface Sediments of Lingding Bay of the Pearl River Estuary, China: Implications for the Nonclassical Crystallization Pathway of Gypsum in the Natural Estuary Environment

The mechanism of the nonclassical crystallization pathway of calcium sulfate dihydrate (gypsum) with calcium sulfate hemihydrate (bassanite) as a precursor has been considered in many studies. However, studies on the crystallization of gypsum in natural environments have rarely been reported, especially with regard to natural estuaries, which are one of the most important precipitation environments for calcium sulfate. Here, surface sediments (0–5 cm) of Lingding Bay of the Pearl River Estuary in China were sampled and analyzed. X-ray powder diffraction (XRD) analysis showed that calcium sulfate in the surface sediments mainly existed in the form of gypsum. In high-resolution transmission electron microscopy (HR-TEM) analysis, calcium sulfate nanoparticles were observed in the surface sediments. These particles mainly included spherical calcium sulfate nanoparticles (diameter ranging from 10–50 nm) and bassanite nanorod clusters (sizes ranging from 30 nm × 150 nm to 100 nm × 650 nm), and their main elements included O, S and Ca, with small amounts of N, Si, Na and Mg. The bassanite nanorods self-assembled into aggregates primarily co-oriented along the c axis (i.e., [001] direction). In epitaxial growth into larger bassanite nanorods (100 nm × 650 nm), the crystal form of gypsum could be observed. Based on the observations and analyses, we proposed that the crystallization of gypsum in surface sediments of the natural estuary environment could occur through the nonclassical crystallization pathway. In this pathway, bassanite nanoparticles and nanorods appear as precursors (nanoscale precursors), grow via self-assembly, and are finally transformed into gypsum. This work provided evidence supporting and enhancing the understanding of the crystallization pathway of calcium sulfate phases in the natural estuary environment. Furthermore, the interactions between calcium sulfate nanoparticles and the natural estuary environment were examined.

Chip-Based Dark-filed Microscopy for Sensing the Dynamical Changes of Single Aerosol Nanoparticles

The hygroscopicity of aerosol nanoparticles with the high number concentration in atmosphere significantly affects atmospheric chemistry and visibility, global climate, and human health. Therefore, it is critical to analyze the hygroscopicity of aerosol particles in an atmospheric ambient, where the aerosol's chemical compositions and physical states determine its capability of water uptake. In this work, with the advantages of non-destructive detection, highly sensitivity, and wide-field imaging, a planar photonic chip-based dark-field microscope is developed for real-time imaging and sensing the hygroscopic growth dynamics of single aerosol nanoparticles (diameter around 100 nm) in a label-free manner. The experimental results of single-component and multi-components are well consistent with the calculation results based on extended aerosol inorganic model. This photonic-chip based dark-field microscope can be extended to investigate the physicochemical reactions of various aerosols in real atmospheric environment.

Synthesis of CeO2 and CeO2/C Using Powdered Cellulose and Powdered Cellulose–Sucrose as a Template

CeO2 nanooxide has been synthesized from cerium(III) nitrate using powdered cellulose (PC) and its mixture with sucrose as templates. The removal of templates from composites (PC–Ce(NO3)3 and PC–sucrose–Ce(NO3)3) has been carried out in two ways: via direct burning-out of PC (PC–sucrose) in an air flow and via burning-out of the carbonizate after template pyrolysis. Using UV and IR spectroscopy, X-ray powder diffraction (XRD), and electron microscopy, the influence of the template composition and the method of its removal on the physicochemical characteristics of CeO2 nanoparticles has been studied. A carbon–oxide material CeO2/C has been synthesized by pyrolysis of PC–Ce(NO3)3 and PC–sucrose–Ce(NO3)3 composites. It has been established that the pyrolysis of PC–Ce(NO3)3 and PC–sucrose–Ce(NO3)3 leads to the formation, in the carbonizate, of CeO2 (cerianite) nanoparticles with sizes of 3–4 and 1–2.5 nm, respectively. The average diameter of nanoparticles (according to XRD data) is 3.8 and 2.3 nm. CeO2/C synthesized from the PC–sucrose–Ce(NO3)3 composite contains cerium(III) oxide. All CeO2 nanoparticles in the carbon matrix have a hydroxyl–hydrate cover. The burning of the organic or carbon matrix of the composites leads, regardless of the template used and synthesis conditions, to the formation of CeO2 (cerianite) nanoparticles with the same average diameter of 25 ± 1 nm (according to XRD data), containing an admixture of the Ce(III) phase and having a hydroxyl–hydrate cover. Carbon is present in the material in trace amounts (≤0.15 wt %). The size scatter of CeO2 nanoparticles produced by burning out PC from the PC–Ce(NO3)3 composite is 15–30 nm. In those cases when the organic component from PC–sucrose–Ce(NO3)3 is subjected to burning or the pyrolysis stage of both composites is included in the synthesis process, the appearance of a fraction of larger CeO2 particles (50–60 nm) is observed. The correctness of the obtained data has been confirmed in the course of the model process of hydrogen peroxide decomposition.

Silver-Nanoparticle-Decorated Fused Carbon Sphere Composite as a Catalyst for Hydrogen Generation

The dwindling supply of fossil fuels has resulted in a search for an efficient alternative energy source. Hydrogen gas offers an abundant, clean-burning supply of energy that can be readily produced over time via the water-splitting reaction of sodium borohydride (NaBH4). This study explored the synthesis of a novel catalyst comprised of silver nanoparticles supported on fused carbon spheres (AgNP-FCS). This composite catalyst was then tested for its ability to optimize the hydrolysis reaction of NaBH4. The fused carbon spheres (FCS) were synthesized via a sustainable source, namely a dextrose solution. The synthesized AgNP-FCS catalyst was characterized using transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The average diameter of silver nanoparticles on the catalyst was found to be 30 nm with 3.7% loading. This catalyst was tested under various reaction conditions, including temperatures, doses of NaBH4, and solution pHs. The activation energy of the reaction as catalyzed by AgNP-FCS was determined to be 37.0 kJ mol−1, which was competitive when compared to similar catalysts for this reaction. A study of the reusability of this catalyst suggests that the catalyst can be used multiple times consecutively with no loss in hydrogen generated. This material presents an opportunity for a sustainable catalyst to optimize the amount of hydrogen generated via the hydrolysis of NaBH4.

Size Uncertainty in Individual Nanoparticles Measured by Single Particle Inductively Coupled Plasma Mass Spectrometry.

Single particle inductively coupled plasma mass spectrometry has been used for size measurements of individual nanoparticles (NPs). Here, uncertainties in size analysis based upon two calibration approaches were evaluated: (i) the use of particle size standard and (ii) the use of ion standard solution. For particle size standard approach, the source of uncertainty to determine the target NP diameter was related to the variation in the signal intensities of both target NPs and particle size standard, and the size distribution of the particle size standard. The relative uncertainties of the 50 nm silver NP as the target were 15.0%, 9.9%, and 10.8% when particle size standards of 30 nm, 60 nm, and 100 nm silver NPs were used, respectively. As for the ion standard solution approach, the sources of uncertainty were the concentration of working standard solution, sample flow rate, transport efficiency, slope of calibration curve, and variation in the signal intensity of the ion standard solution and of the target NPs. The relative uncertainties for the 50 nm silver NP were 18.5% for 1 ng/g, 7.6% for 10 ng/g, and 4.7% for 100 ng/g solutions. The lower uncertainty obtained with a high concentration working standard solution is recommended to improve precision on particle size determinations by spICP-MS.

Controlling the Reactivity and Interactions between Hydrogen and Palladium Nanoparticles via Management of the Particle Diameter

AbstractTailoring the interactions between hydrogen and palladium is crucial for numerous industrial and research applications. The fine control of Pd nanoparticles (NPs) diameter is promising to address this problem when other means, i. e. temperature, pressure, or cell voltage, are set by the ongoing process. We investigate the electrochemical behaviour of Pd NPs in the presence of hydrogen over a large range of particle diameters, between 3.8–21.5 nm. The study is carried out in both a three‐electrode setup and a proton pump. A linear relationship between the H/Pd ratios and the NPs diameter is evidenced. The increase in particle size is accompanied by an extension of the loading duration to reach a stable hydride. Beyond H absorption, the HER and HOR kinetics are examined as a function of the particle diameter. The smaller the particle the higher the catalytic activity, with exchange currents ranging between approx. 1.7–9.8 mA mgPd−1.

High-efficiency desulfurization adsorbents loaded with uniformly dispersed nano-metal particles prepared from phytoremediation

Plants can absorb heavy metals from wastewater due to their biological characteristics, and can evenly disperse these metals into plants. Adsorbents prepared by pyrolysis of metal-rich plants have the advantage of uniform metal loading and small metal particles. Therefore, in this study, Pistia stratiotes was cultured in six monometallic solutions of the same concentration to obtain a monometallic desulfurization adsorbent (ACA-I); after screening, culture in three metal solutions of Ni-Co, Ni-Cu and Co-Cu to obtain bimetallic desulfurization adsorbent (ACA-II). The results of TEM and SEM showed that the diameter of metal nanoparticles supported by ACA-II was smaller and more uniform. The adsorption desulfurization performance of PSLAC-Co-Ni, PSLAC-Cu-Ni and PSLAC-Co-Cu was 87 mg g−1, 83 mg g−1 and 80 mg g−1, respectively, which were better than that of ACA-I. However, the physical structures as well as the adsorption desulfurization performance of ACA-II and ACA-I were better than those of adsorbents prepared by conventional methods. This simultaneously solves environmental problems such as heavy metal pollution of water bodies, treatment of metal-rich plants and excessive sulfur content in fuel oil. This study provides a new idea for the preparation and use of loaded adsorbents, and also provides some data support for further industrial applications.

One-Pot Biosynthesis of Carbon-Coated Silver Nanoparticles Using Palm Leaves as a Reductant and a Carbon Source.

In this study, carbon-coated silver nanoparticles (Ag@C NPs) were synthesized with a one-pot hydrothermal method using palm leaves as a reductant and a carbon source. SEM, TEM, XRD, Raman, and UV-vis analyses were employed to characterize the as-prepared Ag@C NPs. Results showed that the diameter of silver nanoparticles (Ag NPs) and the coating thickness could be controlled by changing the amount of biomass and the reaction temperature. The diameter ranged from 68.33 to 143.15 nm, while the coating thickness ranged from 1.74 to 4.70 nm. As the biomass amount and the reaction temperature increased, the diameter of Ag NPs and the coating thickness became larger. Thus, this work provided a green, simple, and feasible method for the preparation of metal nanocrystals.

Enhancement of Methylene Blue Adsorption from ZnO/Activated Carbon Nanocompossites Prepared by Pyrolysis of Molten ZnCl2 with Rice Husks

In this work, we synthesized a facile step pyrolysis of ZnO/activated carbon nanocomposites by using molten ZnCl2 and rice husks in oxygen-limited environment. The mass ratio of molten ZnCl2 and rice husks was chosen from 0 to 5 wt.%, the pyrolysis temperature range from 400 to 800 oC. When the mass ratio of molten ZnCl2 and rice husks was equal to 1.0 and the pyrolysis temperature was at 800 oC, the size of ZnO nanoparticles in diameter was found to be of 10-20 nm. The ZnO/activated carbon nanocomposites exhibited a porous structure with the BET surface area, average pore diameter and pore volume of 643.9 m2/g, 4,76 nm and 0.255 cm3/g, respectively. To investigate the adsorption behavior of methylene blue, batch experiments were performed on all samples. The ZnO/activated carbon sample manufactured at a mass ratio of 1.0 and a pyrolysis temperature of 800 oC has the best methylene blue adsorption capability. The Langmuir isotherm was used to calculate the maximum adsorption capacity of methylene blue, which was 814.9 mg/g. Based on the obtained results, one can suggest that ZnO/activated carbon nanocomposites prepared by the facile pyrolysis route from molten ZnCl2 and rice husks possessing eco-friendly behaviour and low productioncost can be used as a potential adsorbent for wastewater treatment.

Sealing performance in a spiral groove mechanical seal lubricated by magnetic fluid

PurposeMagnetic fluid has excellent function used as lubricants in bearings and mechanical seals, and the purpose of this study is to investigate the sealing performance in a spiral groove mechanical seal lubricated by magnetic fluid.Design/methodology/approachThe sealing characteristic parameters of the lubricating film between the end faces of two sealing rings were calculated based on the Muijderman narrow groove theory for a spiral groove mechanical seal lubricated by magnetic fluid. The film thickness was determined according to the balanced forces on the rotating ring, and the effects of operating conditions, intensity of the magnetic field and diameter of nanoparticles on the sealing characteristics were investigated.FindingsIt has been found that the intensity of magnetic field has a great effect on the viscosity of magnetic fluid, film thickness and friction torque while has a little effect on the mass flux of magnetic fluid. The film thickness, mass flux of magnetic fluid and friction torque increase with the increasing volume fraction, rotating speed and diameter of magnetic nanoparticles in magnetic fluid. The mass flux of magnetic fluid decrease with the increasing closing force, and the friction torque decreases with the increase of media pressure.Originality/valueThe change of intensity of magnetic field can affect the viscosity of magnetic fluid and then changes the sealing performance in a mechanical seal lubricated by magnetic fluid. To reduce the mass flux of magnetic fluid and friction torque, the volume fraction, diameter of solid magnetic particles and film thickness should be 5%–7%, 8–10 nm and 2–9.3 µm, respectively.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-02-2023-0032/

Design of multifunctional graphene oxide-modified nanofiber film with heterostructure (ZnS-CoS@GO@CNFs) for long-term stable potassium ion storage

When transition metal sulfides are used as high-theoretical-capacity anodes for potassium ion batteries (PIBs), their low conductivity and large volume expansion resulted in inferior rate performance and cyclic stability. In this study, multifunctional graphene oxide (GO) was employed to control the diameter and distribution of nanoparticles within composite fibers, which improved their conductivity and tensile deformation. In addition, a three-dimensional conductive carbon network composed of heterostructures and GO (ZnS-CoS@GO@CNFs) accelerated the kinetics and stabilized potassium ion storage. As the anode material of PIBs, the composite provided an excellent rate performance of 210 mA h g−1 at 3 A g−1, and after 2800 cycles under a large current of 2 A g−1, the capacity retention rate was 97.7% (171 mA h g−1). Furthermore, when the nanofiber film was used as a self-supporting anode, it maintained a stable capacity output (302 mA h g−1 after 100 cycles at 0.1 A g−1). A foldable pouch cell was assembled using a potassium ion hybrid super-capacitor, and it was found to operate safely and normally under multiangle repeated bending and final recovery; further, it provided a high energy density (134 W h kg−1) and power density (5815 W kg−1). The excellent electrochemical properties determined here further reveal the application prospects of multifunctional GO composite fiber film.

SURG-03. LAYER-BY-LAYER CORE-SHELL NANOPARTICLES FOR THE DELIVERY OF HDAC INHIBITORS TO THE CENTRAL NERVOUS SYSTEM

Abstract Diffuse midline gliomas (DMGs) present unique challenges in pediatric cancer care. The location of DMGs often renders the tumor inoperable and radiation produces only a temporary effect. One promising approach in DMG treatment is histone deacetylase (HDAC) inhibitors. However, HDAC inhibitors are difficult to deliver to primary central nervous system (CNS) tumors because of low blood-brain barrier (BBB) permeability and poor accumulation in tumor tissues. The BBB permeability is particularly restricting for DMGs, which maintain a relatively intact BBB. To overcome these delivery challenges, we developed a new polymer-lipid core-shell nanoformulation for the delivery of HDAC inhibitors to the CNS that does not rely on polyethylene glycol (PEG) for colloidal stability. Removing PEG allows for surface charge manipulation to generate charged nanoparticles amenable to layer-by-layer assembly with alternately charged polyelectrolytes. This modular platform allows the addition of targeting moieties to enhance the delivery of HDAC inhibitor core-shell nanoparticles across the BBB and into DMG cells. HDAC inhibitors panobinostat and quisinostat were loaded into core-shell nanoparticles comprised of a poly(lactide-co-glycolide) (PLGA) core and a phospholipid shell. Nanoparticles were characterized using dynamic light scattering and transmission electron microscopy exhibiting favorable properties for in vivo delivery (panobinostat nanoparticle diameter 91.6 ± 1.0 nm, polydispersity index 0.115 ± 0.013). The release of HDAC inhibitors from layered and unlayered core-shell nanoparticles was investigated using high-performance liquid chromatography. The deacetylating activity of nanoencapsulated agents was confirmed in vitro in patient-derived DMG neurosphere models. CNS pharmacokinetic parameters are currently being investigated after intravenous delivery of drug-loaded nanoparticles in non-tumor-bearing mice, including cerebrospinal fluid and brain tissue concentrations of the encapsulated agents. Future studies will investigate brain biodistribution of core-shell HDAC inhibitor nanoparticles in orthotopic DMG tumor-bearing mice, comparing intravenous and local delivery strategies.