Sphere-like Particles Research Articles

Effect Annealing Temperature on Pure and Al-Doped Iron Oxide Thin Films for Formaldehyde Gas Sensing Application

The present study employs chemical spray pyrolysis to prepare pure and Al-doped α-Fe2O3 thin films with different aluminium concentrations. Subsequently, annealed at 450 °C and investigated the effect of annealing temperature on structural, morphological, optical, chemical and gas sensing properties. Field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) studies were adapted to examine the morphologies and microstructural properties of the α-Fe2O3-based thin films. All the films were polycrystalline with rhombohedral structure, and the (104) plane was confirmed to be the favoured orientation. Deposited thin films were seen to have agglomerated, superimposed sphere-like particles on their surfaces in AFM and FESEM micrographs. Raman spectroscopy analysis and XPS were used to examine the film’s symmetry and structural characteristics. The optical band gap of the deposited thin films is determined using a Tauc plot.Pure and Al-doped thin film’s formaldehyde sensing capability was examined based on aluminium (Al) doping concentration. The results of the experiments showed that the gas-detecting capabilities have been significantly enhanced by the optimal content of Al added to the α-Fe2O3 lattice.

Effect of linearly polarized microwaves on nanomorphology of calcium carbonate mineralization using peptides

Microwaves are used for diverse applications such as mobile phones, ovens, and therapy devices. However, there are few reports on the effects of microwaves on diseases other than cancer, and on physiological processes. Here, we focused on CaCO3 mineralization as a model of biomineralization and attempted to elucidate the effect of microwaves on CaCO3 mineralization using peptides. We conducted AFM, ζ potential, HPLC, ICP-AES, and relative permittivity measurements. Our findings show that microwaves alter the nanomorphology of the CaCO3 precipitate, from sphere-like particles to string-like structures. Furthermore, microwaves have little effect on the mineralization when the mineralization ability of a peptide is high, but a large effect when the precipitation ability is low. Our findings may be applicable to not only the treatment of teeth and bones but also the development of organic–inorganic nanobiomaterials. This methodology can be expanded to other molecular/atomic reactions under various microwave conditions to alter reaction activity parameters.

Ce-Zr UiO-66 MOF as recyclable heterogeneous catalyst for selective N-methylation

Metal-organic frameworks (MOFs) are proven heterogeneous recoverable catalysts in a number of organic transformations. However, their role in the reaction of amines with dialkyl carbonates has only been partially investigated. In this paper, the catalytic potential of Ce-Zr UiO-66 MOF towards the N-alkylation of secondary amines with dimethyl carbonate has been investigated. The desired MOF catalyst was prepared by the solvothermal method and its morphology, texture, porosity, functionality, and crystallinity were examined before its catalytic investigation. The MOF consisted of sphere-like particles with a surface area of 272 m2/g and an average pore size of 3.4 nm. Under the optimized conditions, the aromatic and heterocyclic amines yielded the N-methylated derivatives as the sole or the major product in the presence of Ce-Zr UiO-66 MOF. The maximum methylation percentage achieved was 100%. The reaction followed the pseudo-first-order rate kinetics and the heterogeneous bimetallic Ce-Zr UiO-66 MOF was reused four times without any significant activity loss. Thus, the Ce-Zr UiO-66 MOF serves as an efficient, selective, and reusable heterogeneous catalyst in N-methylation reactions.

Synthesis, structural, and microwave absorption properties of hematite (α-Fe2O3) and maghemite (γ-Fe2O3)

This work demonstrated the synthesis, structural, and microwave absorption properties of hematite (α-Fe2O3) and maghemite (γ-Fe2O3) nanopowders. The desired samples are successfully synthesized from the natural ironstone of Indonesia by using the coprecipitation method. The variations of acidic environments during the synthesis process (i.e., pH 6 and 7) were done to obtain the maghemite and hematite phases. The combination of x-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements was used to investigate the crystal and microstructure, respectively. Meanwhile, the vector network analyzer (VNA) was performed to examine the microwave absorption properties at x-band frequency. The structural measurements of the samples confirmed the formation of single-phase maghemite and hematite phases for precipitation pH 6 and 7, respectively, which showed the change in morphology after the precipitation process and sphere-like agglomerated particles of samples. The results Debye–Scherrer equation indicates that the crystal size of precipitated samples is on the order of nanometers. The microwave absorption characteristics through VNA measurements showed enhanced microwave absorption properties after the precipitation process; the RL max of natural ironstone increased from −4.39 dB to −10,99 and −11,72 dB for S6 and S7 samples, respectively. Generally, the hematite and maghemite reveal the same pattern of absorption peaks. The RL max of natural ironstone, S6, and S7 samples were observed at 10.52, 11.04, and 11,06 GHz, respectively. These results revealed that the variation of acidic environments during the synthesis process influenced the structure and microwave absorption.

Synthesis of spherical-like β-Si3N4 powder by direct nitridation of silicon saw dust

ABSTRACT Spherical-like β-phase silicon nitride (β-Si3N4) powder has been synthesized by direct nitridation of silicon saw dust recovered from the photovoltaic industry in ammonia gas (NH3) at 1300°C with calcium fluoride (CaF2) as additive. The X-ray diffraction (XRD) analysis indicates that the formation of β-Si3N4 is enhanced and accelerated in NH3 compared to nitrogen (N2). The scanning electron microscope (SEM) examination shows that, compared with N2, NH3 contributes to the formation of spherical-like particles, and all irregular silicon particles are transformed into spherical-like β-Si3N4 particles in the NH3 atmosphere. These results indicate that the NH3 atmosphere is conducive to the formation of submicron spherical-like β-Si3N4 particles. A complete submicron spherical-like Si3N4 powder with 93.12 wt% β phase has been synthesized by direct nitridation of silicon saw dust assisted with 5 wt% CaF2 additives in NH3. The mechanism for the formation of the spherical-like β-Si3N4 powder has also been discussed.

Characterization and synthesis mechanism of Co3O4 nanoparticles synthesized by the emulsion detonation method

Tricobalt tetraoxide (Co3O4) nanoparticles have excellent applications in the fields of electricity, photocatalysis, and ceramics, whereas conventional synthesis methods require sophisticated equipment, strictly controlled conditions, and long duration. Herein, a new method for the synthesis of Co3O4 nanoparticles was proposed. In this emulsion detonation method, the precursor cobalt nitrate hexahydrate (Co(NO3)2·6H2O) was added during the production of the explosives and was therefore more uniformly dispersed than in other detonation methods. The preparation and detonation durations of the explosives were on the scale of minutes and microseconds, respectively, which are much shorter than those in other nanomaterial synthesis methods. The collected products were briefly purified and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectrometer, field emission scanning electron microscopy, and field emission transmission electron microscopy. Cyclic voltammetry and galvanostatic charge–discharge measurements were performed. The results show that the synthesized products were of high purity and consisted mainly of sphere-like particles with a dimensional distribution of approximately 50 nm. The electrochemical properties of these Co3O4 nanoparticles were similar to those synthesized by conventional methods. Combined with the detonation theory and the initial composition of the products, the analysis showed that the synthesis mechanism is mainly divided into two stages: formation and polymerization. Therefore, this approach could provide a new and effective synthesis method for the low-cost production of Co3O4 nanoparticles.

Influence of the calcination duration of g-C3N4/TiO2 “veggie-toast-like” photocatalyst on the visible-light triggered photocatalytic oxidation of bisphenol A

Two commercially available TiO2 (hexagonal-like and spherical-like particles) were used to investigate the effect of g-C3N4 “melting” on the photocatalytic properties of g-C3N4/TiO2 composites. Improvement in the contact between the components was observed when they were thermally treated at 350 °C for an extended period of time (between 2 and 72 h) due to the partial melting and phase fusion of g-C3N4. Consequently, the enhanced contact between the phases allows easier injection of photogenerated electrons from the conduction band of g-C3N4 into TiO2, improving charge carrier separation. The prepared composites were tested for bisphenol A degradation under visible-light illumination, which showed that the components that had been calcined for 24 h performed better due to the improved charge carrier separation. Superoxide anionic radicals and photogenerated holes were identified as active species in the photooxidation experiments conducted under visible-light illumination.

Amphiphilic dendrons as supramolecular holdase chaperones.

The aggregation of incompletely or incorrectly folded proteins is implicated in diseases including Alzheimer's, cataracts, and other maladies. Natural systems express protein chaperones to prevent or even reverse harmful protein aggregation. Synthetic chaperone-like systems have sought to mimic the action of their biological counterparts but typically require substantial optimization and high concentrations to be functional, or lack programmability that would enable the targeting of specific protein substrates. Here we report a series of amphiphilic dendrons that undergo assembly and inhibit the aggregation of fragment 16-22 amyloid β protein (Aβ16-22). We show that monodisperse dendrons with hydrophilic tetraethylene glycol chains and a hydrophobic core based on naphthyl and benzyl ethers undergo supramolecular assembly in aqueous solutions to form sphere-like particles. The solubility of these dendrons and their assemblies is tuned by varying the relative sizes of their hydrophilic and hydrophobic regions. Two water-soluble dendrons are discovered and shown, via fluorescence experiments with rhodamine 6G, to generate a hydrophobic environment. Furthermore, we demonstrate that sub-stoichiometric concentrations of these amphiphilic dendrons stabilize Aβ16-22 peptide with respect to aggregation, mimicking the activity of holdase chaperones. Our results highlight the potential of these amphiphilic molecules as the basis for a novel approach to artificial chaperones that may address many of the challenges associated with existing synthetic chaperone mimics.

Giant baroresistance effect in lanthanum-strontium manganite nanopowder compacts

Nowadays, there is an urgent issue in creating highly sensitive current, magnetic field, temperature, and pressure sensors. For this purpose, a magnetic La0.6Sr0.3Mn1.1O3 (LSMO) nanopowder has been synthesized by atomization hydrolysis and compacted under different pressures up to 1600 MPa. Their phase composition, crystal structure, morphology, magnetic, magneto-resonance, transport, magnetoresistance (MR), and baroresistance (BR) properties have been comprehensively studied. It has been shown that the LSMO nanopowder is a single-phase perovskite and consists of spherical-like particles with an average size of 37 nm. As the pressure increases to 1600 MPa, the filling factor in the compacts increases, decreasing the average distance between particles. In the room temperature range, the LSMO nanopowder is in a ferromagnetic state with a Curie temperature TC = 367 K and does not depend on the compacting pressure P. The conductivity is thermally activated by hopping conduction along the nearest particles. With increasing P, a monotonic decrease in resistivity is due to reducing the distance between particles. The temperature dependences of the MR have a tunneling character. Giant BR effect with the establishment of the following important applied properties has been found: (i) the BR effect is not limited by the Curie temperature and is observed both in the ferromagnetic and paramagnetic states; (ii) the BR effect under constant pressure slightly depends on the temperature in a wide range from – 193 to + 127 ℃; (iii) in the pressure range from 0 to 400 MPa, the BR effect has the highest sensitivity of 0.1%/MPa. The obtained results and established regularities in the LSMO nanopowder compacts can be used to create pressure sensors for modern intelligent process control systems.

Fabrication of dual-functional cellulose nanocrystals/fluorinated polyacrylate containing coumarin derivatives by RAFT-assisted Pickering emulsion polymerization for self-healing application

Polymeric coatings are easy to be damaged by harsh environment condition, which causes cracks and loss of function. Inspired by the natural self-healing phenomenon, we successfully synthesized dual-functional cellulose nanocrystals/fluorinated polyacrylate containing coumarin derivatives by RAFT-assisted Pickering emulsion polymerization. The amphiphilic and photo-responsive copolymer, PDMAEMA-b-PGMA-b-P(HFBA-co-VBMC) was synthesized by RAFT process, followed by characterization using FT-IR, SEC, 1H NMR and UV–vis. The cellulose nanocrystals were modified by the copolymer, which were confirmed via XPS, UV–vis and so on. Besides, the droplet size of Pickering emulsion gradually increased and the creaming layer gradually decreased as the pH value increased. The TEM result showed that the modified cellulose nanocrystals were effectively anchored on the outside of latex particles. The size of the spherical-like latex particles increased and the stability of latex particles was worse with increasing pH value. Finally, the finished fabric had excellent water resistance due to the combination of micro- or nanoscale hierarchical structure and low surface energy. Moreover, the latex film exhibited excellent repeatability of self-healing ability. The fabric coating achieved the intrinsic and superficial dual-functional self-healing performance by the reversible [2 + 2] cycloaddition of coumarin groups. This strategy provides a powerful guide for preparing the high-performance waterborne fluorinated polyacrylate coating.

Biomimetic one-pot preparation of surface biofunctionalized silica-coated magnetic composites for dual enzyme oriented immobilization without pre-purification

Surface functioned magnetic silica particles are efficient carriers to achieve facilitated separation and recycling of biocatalysts. However, traditional methods of modifying magnetic silica particles required time-costly sequential coating and surface modification steps and toxic solvents. Herein, a green and efficient routine was proposed to prepare the surface modified silica-coated magnetic microspheres (SCEs@SiO2 @Fe3O4) in one-pot. The elastin-like polypeptides (ELPs)-SpyCatcher chimera (SCEs) were purified by inverse transition cycling with high yield (275 mg/L) and incorporated into the magnetic silica spheres based on the biomimetic silicification capability of ELPs as proved by the EDS and SEM mapping. No SCEs leaked was observed within 48 h, indicating excellent stability in buffer. Then, the biofunctionalized carriers were used to purify and immobilize the target dual enzymes (xylanase-linker-SpyTag-linker-lichenase, bienzymes) directly from the crude cell lysis solution by the spontaneous isopeptide bond reaction between SpyCatcher and SpyTag. The immobilized bienzymes were sphere-like magnetic silica particles with uniform size, which had good magnetic responsiveness. The immobilization yield, immobilization efficiency and activity recovery for xylanase were 86%, 84 % and 72 %, while for lichenase was 92 %, 86 % and 79 %, respectively. Besides, the immobilized bienzymes showed good reusability (>60 %, 10 times for xylanase, >95 %, 8 times for lichenase). The SCEs modified silica-coated magnetic microspheres are expected to provide versatile platforms for single-step of purification and immobilization of multienzymes, offering great potentials in the field of biocatalysis.

Optoelectric Properties of Doped Carbon Dot Nanostructures

Carbon dots (C-Dots) can be defined as spherical-like carbon particles (graphitic fragments) with sizes less than 10 nm. Typically, C-Dots exhibit ample room temperature photoluminescence (PL) whereby the PL properties of C-Dots with a well-defined crystalline core is related to the size or conjugated domains of C-Dots accompany with contribution from the surface state, conjugated core, molecular configuration, and so on. However, up to date the exact mechanism of the PL origins of C-Dots depends on synthesis path and remains unsettled [1-3]. In this contribution we will discusses the synthesis, characterization and origins of PL properties of doped C-Dots their potential for applications as absorbers in solar cells. We discuss to use nitrogen doped C-Dots as active absorbing layer in a solar cell and how the electrical, optical, and chemical properties can be engineered by doping. We demonstrate that the doping can be efficiently used to modify the band structure of the C-Dots and meet the requirements for application in solar cells. To rationalize the measured experimental data, we also calculated using DFT in the sTDA approximation the absorbance spectra of pristine and nitrogen doped C-Dots. For computationally feasibility the diameter, d = 2.3 nm, of the C-Dots is chosen to be at the lower end of experimentally observed size distribution and the C-Dots consist of 3 carbon layers. Subsequently, these C-Dots have potential to be used as an absorbing material in next-generation solar cells for high energy photons to be absorbed by a lower bandgap transporter.

Suppressed Volume Change of a Spray-Dried 3D Spherical-like Si/Graphite Composite Anode for High-Rate and Long-Term Lithium-Ion Batteries

Morphology plays a vital role in controlling the volume variation in Si-based anode materials and enhances lithium-ion battery performances. Here, we demonstrated advanced techniques that combine electrostatic self-assembly and spray-drying methods to form 3D spherical-like silicon/graphite (denoted “Si/G”) composite anode materials. This spherical morphology alleviates issues relating to silicon volume changes that occur in high-rate lithium-ion batteries. Commercial graphite (G) flakes were initially mixed with silicon nanoparticles (ca. 50 nm) to form a bare-Si/G composite through electrostatic interaction; spherical-like composite particles were then obtained through single and double spray-drying processes, giving samples SD1-Si/G and SD2-Si/G, respectively. We examined the charge/discharge characteristics of the fabricated electrodes (CR2032-type coin cells) in the voltage range 0.02–1.5 V (vs Li/Li+). The as-fabricated bare-Si/G, SD1-Si/G, and SD2-Si/G half-cells provided initial discharge specific capacities of 897, 866, and 1020 mA h g–1, respectively. The SD2-Si/G half-cell shows better cycling stability at a high current rate of 400 mA g–1 than the SD1-Si/G and bare-Si/G half-cells due to effective inhibition of the volume change in the more stable spherical structure of the SD2-Si/G composite, as evidenced through in situ dilatometry. Thus, the spherical Si/G composite material produced through this simple spray-drying process had structural characteristics that could effectively resist silicon’s high expansion rate, lower the production rate of broken silicon particles, and improve the electrochemical performance of the anode.

Synthesis and Characterization of Ibuprofen Delivery System Based on β-cyclodextrin/Itaconic Acid Copolymer

This study aims at preparation and characterization of drug delivery system based on grafted beta-cyclodextrin (β-CD) with itaconic acid (IA) using free-radical copolymerization technique, in the presence of N, N'-methylene bisacrylamide (BIS) and ammonium persulphate (APS) as a crosslinker and an initiator, respectively. The obtained copolymer (CD-PIA) was characterized using Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray diffraction patterns (XRD), transmission and scanning electron microscopes (TEM and SEM). Ibuprofen (IBU), as an anti-inflammatory drug model, was loaded during the preparation. The kinetic of the copolymerization was investigated in terms of grafting yield (GY %), grafting efficiency (GE %) and monomer conversion (%). Moreover, in vitro IBU release and kinetic of released using the different mathematical models (0-order, first-order and Higushi) were carried out in simulated gastric and intestinal fluids (SGF and SIF at pH 1.2 and 7.4, respectively) at 37 °. The results proved the successful preparation of the target copolymer with irregular spherical-like shape and particle size around 14 - 27.7 nm. After IBU loading, the copolymer exhibited thermal stability with crystalline nature. Also, the study showed that the synthesized copolymer, especially which high IA content is controlled the release of IBU after 4 h. Besides, it could be used as a potential IBU delivery system with sustained-release followed the first-order kinetic over 24 h.
 HIGHLIGHTS
 
 The nanogels drug carriers used for nonsteroidal anti-inflammatory drugs to overcome the unfavorable release in the stomach due to unforeseen pH alterations
 The polymeric grafted β-CD derivatives using IA represent a unique class of the host materials with tunable inclusion properties and high affinity for Ibuprofen release
 In vitro kinetic of IBU released showed the best fit with first-order model
 
 GRAPHICAL ABSTRACT

Enhanced photosensitivity of heterostructure SiO2/Bi2WO6/GO composite nanoparticles

The Bi2WO6, Bi2WO6@GO, SiO2/Bi2WO6, and SiO2/Bi2WO6@GO nanocomposites were synthesized using a simple process. X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR), EDX mapping investigations confirmed the successful synthesis, related chemical bonding, and elements in the structure. According to the TEM and FESEM images, composite nanoparticles consisting of cubic-like Bi2WO6 and regular spherical-like particles of SiO2 between the GO sheets. The strong emission color of green under ultraviolet excitation was obtained. The radiation sensitivity of the SiO2/Bi2WO6@GO nanocomposite under the 241Am alpha source was the best compared with other samples. It was observed that the incorporation of SiO2 and reduced graphene oxide in composite structures can lead to further sensitivity of ionizing radiation and luminescence intensity at room temperature. Furthermore, prepared SiO2/Bi2WO6 NPs showed a high decolorization efficiency of MB dye (98.2%) under UVA irradiation for 100 min. These results present a promising potential for applications in photonic devices.

High Performance of UiO-66 Metal–Organic Framework Modified with Melamine for Uptaking of Lead and Cadmium from Aqueous Solutions

In this paper, UiO-66 metal–organic framework (MOF) was prepared by a hydrothermal method and modified consequently with melamine (MUiO-66), as so as enhance the adsorption properties of these materials in liquid-phase adsorption. With respect to this, the adsorption of lead and cadmium divalent ions was performed under varying conditions of pH, metal ion concentration, contact time, adsorbent dose and temperature. Morphology, texture properties, functional groups, crystallinity and thermal properties of both MOFs were examined. UiO-66 composed of sphere-like particles and covered by layers of melamine with enhancing in crystallinity and active sites as well as the total surface area increased from 1080 to 1160 m2/g. The modified UiO-66 with melamine (MUiO-66) showed a notable adsorption capacity of 177.5 and 146.6 mg/g for Pb and Cd(II) ions, respectively. Adsorption of both metals fitted well with the pseudo-second-order kinetic and Langmuir models and controlled by a physisorption mechanism at pH of 5. Also, adsorption process is an endothermic in nature and desorption is achieved well for three cycles by MUiO-66. Therefore, UiO-66 and MUiO-66 obtained in this work have a great promise in adsorption of heavy metals such as Pb and Cd(II) ions from wastewater.

A durable and sustainable superhydrophobic surface with intertwined cellulose/SiO2 blends for anti-icing and self-cleaning applications

Poor wear resistance and the use of toxic chemicals restrict the marketization of most traditional superhydrophobic surfaces. The present work provides a method to prepare a durable and non-toxic superhydrophobic coating on the surface of a cotton fabric. Thermal polymerization of spray drying was used to obtain uniform structure of TEMPO-oxidized cellulose (TOC) with nano silica (SiO2), for achieving well-combined rough sphere-like micron particles with hierarchical dimensions, which were then immersed into isocyanate (IPDI) and polydimethylsiloxane (PDMS) respectively along with cotton fabric to construct a superhydrophobic coating on the fabric surface. The surface morphology, chemical structure, roughness and wettability of TOC-SiO2/PDMS surface were studied by adjusting the mass ratios of SiO2 to TOC. The optimal superhydrophobicity was obtained while the mass ratio of SiO2 to TOC was 1:1, displaying a water contact angle (CA) of 158.6°. The introduction of the intertwined TOC-SiO2 blends can construct a hierarchical micro-nano structure to enhance the hydrophobicity, simultaneously improve the mechanical durability of the superhydrophobic surface to prevent multiple peeling and friction damage, as well as outstanding chemical stability in a variety of harsh conditions.

Effect of Hydrothermal reaction times and temperature-dependent Spherical like NiCo2O4 nanoparticles for supercapacitor application

ABSTRACT The effects of reaction times and temperatures on the electrochemical capacitance characteristics of NiCo2O4 nanoparticles (NPs) are investigated. The hydrothermal reaction temperatures and times play critical parts in the creation of unique hierarchical NCO based on morphological evolution in this work. The calcination temperature 400 °C was fixed using TG-DTA study. The crystal structure and phase identification is investigated from XRD analysis. FTIR peaks in the region of 700-500 cm−1 confirmed the presence of the Ni-O and Co-O bond. The spherical-like nanostructure NiCo2O4 particles are visualized from SEM, HR-SEM and HR-TEM analyses. From the EDS spectra, the atomic percentage composition of the elements namely, Ni, Co and O were observed. The optimized sample was subjected to a VSM and CV analyses, which revealed that it is superparamagnetic nature (Ms = 4.8298 emu/g) and Pseudocapacitive behaviour with highest capacitance value of 534 Fg−1 with the lower scan rate of 10 mVs−1.

Metal-organic framework-derived ZrO2/NiCo2O4/graphene mesoporous cake-like structure as enhanced bifunctional electrocatalytic cathodes for long life Li-O2 batteries

Metal-organic frameworks (2D MOFs) have great potential to improve the electrochemical performance of Li-O2 batteries with high O2 accessibility, the catalytic activity of the open active metal sites, and large specific surface areas. Herein, we prepared a 3D hierarchical ZrO2@NiCo2O4/GNS (ZNCO) framework as cathode catalysts in Li-O2 batteries that have been developed to synthesize with Zr/Ni to Co molar ratio of 0.1:1:2 by a facile hydrothermal method. The coating of foreign Zr4+ ions into the nickel cobaltite matrix, have superior oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) bifunctional activity, and allowed the formation of 3D dimensional networks for oxygen diffusion, electrolyte impregnation, and has very ORR/OER low overpotential due to Zr insertion. Moreover, the ZrO2 coated shell increases the electronic conductivity, porosity, specific surface area, and protects the core and interstitial decoration against lithium peroxide passivation (Li2O2). The electrochemical performance of the 3D hierarchical ZrO2@NiCo2O4/GNS nanocomposite delivers a higher discharge capacity of 9034 mAh g–1 at 50 mA g–1 and a superior cycling performance up to 100 cycles with a limited capacity of 1000 mAh g−1 at 100 mA g−1. An ORR/OER mechanism was suggested to illustrate the interesting growth of spherical-like particle and film-like Li2O2 deposits at the different cycles for the ZrO2@NiCo2O4/GNS cathodes. Such MOF-derived; hierarchical porous nanocomposites can lead to high-performance efficient bifunctional electrocatalysts and enables the formation and decomposition of discharge products (Li2O2) during the discharge-charge process.

Effect of particle shape on raceway size and pressure drop in a blast furnace: Experimental, numerical and theoretical analyses

Experiments and simulations are conducted to explore the changing laws of blast furnace (BF) raceway morphology and pressure drop with cylindrical particles. Experimental data show that there are five typical stages for the pressure drop during the raceway formation. The closer the aspect ratio (Ar) of the particle to 1, the bigger the raceway size and the wider the particle moving band will be. When the raceway is in stable stage, the pressure drop can be ascribed to the cooperative action of the bed height, inlet gas velocity and Ar. Numerical results reveal that the formation of large raceway for sphere-like particles is due to the small drag and contact forces. The contact forces in the prolate particle system are very large and thus result in a small raceway. Finally, the influence of particle shape is employed to improve a raceway size predictive correlation which can increase the average calculational accuracy by 3.4%.