Journal of Nanoparticle Research最新文献

In this study, a computational analysis based on density functional theory is conducted to study the elastic, mechanical, vibrational, and thermodynamic properties of novel chalcogens, Ag₂BeSnX₄ (X = S, Se, and Te). We used the generalized gradient approximation (GGA) within the framework of density functional theory (DFT). The mesh parameter values (a and c) were calculated using the X-ray diffraction method. The calculated elastic constants indicate that the bond strength along the [1 0 0] directions is stronger than that along the direction [0 0 1]; according to the Born-Huang stability criterion, we can see that they are mechanically stable. A high value of the ratio (B/G) is associated with ductility for Ag₂BeSnX₄ (X = S, Se, and Te) materials. Additionally, the Raman shifts of all samples are calculated. Between 10 and 1000 K in temperature, the vibrational mode shifts were calculated for three chalcoginides. The thermal behavior of these movements shows that these structures can undergo deformation with increasing temperature. These results suggest a first contribution to the understanding of the effect of temperature on the vibrational modes of three kesterite structures Ag₂BeSnX₄ (X = S, Se, and Te) and consequently on their structures. The heat capacity (({C}_{V})), free energy ((F)), entropy ((S)), and enthalpy ((H)) are also computed. The kesterite phase of the Ag₂BeSnX₄ (X = S, Se, and Te) structures aligns with theoretical findings in elastic properties, exhibiting superior elastic properties. These attributes are valuable for the design of optoelectronic devices.

Nano-priming is an emerging application of nanotechnology in agriculture intending to increase crop yield and nutritional quality while reducing fertilizer applications. This study aimed to investigate the effects of seed priming with citrate-coated CoFe₂O₄ nanoparticles (NPs) suspensions (10, 20, and 40 mg NPs L⁻¹) on the life cycle of the Phaseolus vulgaris L. OTI cultivar and evaluate the technology costs. The effect of nano-priming was assessed in the germination, flowering, and harvest stages. Unprimed and hydro-primed seeds were negative and positive controls, respectively. Nano-priming with CoFe₂O₄ NPs had no effect neither on the germination nor on plant nutrition (in the flowering stage) of OTI beans compared to unprimed and hydro-primed seeds. In contrast, nitrogenase activity (343.3 ± 1.1 µmol h⁻¹ plant⁻¹ of C₂H₄) was detected in the plants from the 40 mg kg⁻¹ nano-primed seeds. The K concentration of progeny seeds from nano-priming with 10, 20, and 40 mg NPs L⁻¹ increased significantly by 3%, 16%, and 13% compared to the control seeds. The Zn concentration in the seeds from nano-priming with 10 mg NPs L⁻¹ was 27% higher than in the control and 28% higher than in the hydro-primed seeds. When nano-priming with 40 mg NPs L⁻¹, the Zn concentration was 5% and 6% higher than the control and hydro-primed seeds. The calculated cost of nano-priming seeds per ha ranged from 121 to 143 USD. In this regard, nano-priming of bean seeds with citrate-coated CoFe₂O₄ NPs could be a low-cost approach to achieve nutritional security and agricultural sustainability.

Ultra-small iron oxide nanoparticles (USNPs) have attracted particular attention in the past 15 years as perspective contrast agents for MRI. Unfortunately, the synthesis of such small nanoparticles with high contrast properties and water dispersibility is still challenging. This paper presents a study on the influence of synthetic conditions on the structure and the properties of hydrophilic iron oxide nanoparticles obtained by a simple single-step thermal decomposition in diethylene glycol at 230–235 °C. The samples were studied using X-ray diffraction, Mössbauer and infra-red spectroscopy, transmission electron microscopy, vibrating sample magnetometry, MRI, and dynamic light scattering. All the obtained samples are of spinel structure (Fd-3 m), specific to both magnetite and maghemite. With an increase in the synthesis time from 1 to 8 h, the crystallite size of the series with C(Fe(acac)₃) = 30 mM changed from 1.8 ± 0.2 to 4.7 ± 0.5 nm, the average size according to TEM changed from 3.3 ± 0.8 to 3.8 ± 0.4 nm, and the saturation magnetization from 13.9 ± 0.3 to 83.3 ± 1.7 A•m²/kg, which is close to the values of bulk iron oxide. The same tendency was revealed with the increase in the concentration of C(Fe(acac)₃) from 30 to 120 mM for 1 h of synthesis. An increase in the synthesis time for 60- and 120-mM solutions did not significantly change the crystallite size and the magnetic properties. It was shown that the samples obtained using this approach have unexpectedly high values of r₂-relaxivity, up to 235 mM⁻¹•s⁻¹, which the highest published for USNPs. The studied method of water-soluble USNPs is promising for use in creating T₂-contrast agents for MRI.

Some physical properties of M-doped (M = Ag, Au) single-walled (6,0) silicon-carbide nanotubes (SWSiCNTs) were studied by first-principles simulations based on density functional theory within local spin density approximation. The band structures, density of states, and the influence of defects on the magnetism are studied for the Ag- and Au-doped SiC nanotubes. We obtained that the electronic properties of the SWSiCNTs are significantly changed by metal introduction and these systems show magnetic properties. While Ag- and Au-doped single-walled (6,0) SiC nanotube configurations, the width of the energy gaps of spin-up states decreases, and these systems show metallic character. The analysis of the partial density of states shows that the electronic states mainly come from the contribution of the p electrons of carbon and d electrons of transition metal atoms. The total energy calculations for Ag- and Au-doped SiC nanosystems show the stability of the antiferromagnetic phase. Our calculations show that SiC nanotubes doped with Ag and Au can be transformed into a new ferromagnetic material with half-magnetic character, and these nanomaterials are promising candidates for spintronics device applications.

This study investigated the possibility of extending the soot morphology analyses to acoustically agglomerated soot deposited on the surface of smoke alarms and of applying the validity of soot analysis for unique chemical signatures in the field of fire investigations. Through collecting soot samples, including agglomerated soot acquired from smoke alarms, this research presents a pioneering stride in soot morphology data analyses conducted by leveraging advanced deep learning methodologies. Preliminary outcomes underline that the proposed convolutional neural network model has the potential to decode intricate soot characteristics and to distinguish soot particle images between diverse fuel types and burning conditions. In particular, for the acoustically agglomerated soot collected by smoke alarms, it was also found possible to decode their intricate morphology by applying the proposed data-driven approach.

Colloidal particles fabricated using lithographic methods are used in micro-nanoengineering as well as biomechanical and chemical engineering. Much of the research in this field deals with close-packed colloidal particles in the form of continuous two-dimensional (2D) surface structures or membranes. The most common approach to modifying the arrangement and spacing of colloidal particles involves etching or the fabrication of micro-nanoimprinted structures at the micro- or nanoscale. In the current study, three-dimensional (3D) micro-printing was used to fabricate grid and honeycomb structures with precise control over the spatial distribution and height. We achieved a uniform distribution of polystyrene micro spheres across the surface of the structures by performing a variation of the floating assembly method referred to as drop deposition, which when implemented using methanol was shown to enhance the dispersal of microspheres in the mixture by reducing the London diverse force (LDF). The application of ultrasonic vibrations during microsphere deposition was shown to facilitate the integration of PS microspheres within the underlying lattice. We also found that methanol is highly effective in the removal of accumulated microspheres. The fabrication of grid and hexagonal structures spaced at intervals of 6, 6.5, and 7 μm followed by the deposition of PS microspheres (diameter = 6 μm) was shown to increase the water droplet contact angle from 103° (close-packed) to 110° (square arrangement) and 123° (hexagonal arrangement).

Enormous advances have been made in the synthesis of metal nanoparticles (NPs) affording a high degree of control over their size, shape, and composition. In recent years, a growing effort has been dedicated to incorporating principles of green chemistry in different aspects of NPs, ranging from reagents/solvents to their fate in the environment. In this report, we focus on the use of Cyrene (dihydrolevoglucosenone) as an alternative green solvent for the synthesis of metal NPs. We begin with the synthesis of Ag NPs, given their prominence in the literature. Through control reactions, we show that Cyrene has a dual role of solvent and reducing agent. Additionally, the conversion yield for the Ag NPs synthesis was studied with respect to temperature and the Ag precursor. We then expand on the synthetic methodology to access Pd, Pt, and Bi NPs. The functionality of the synthesized NPs is assessed by employing them as electrocatalysts for furfural reduction and the hydrogen evolution reaction. We envision the use of Cyrene as a green solvent can be extended toward the synthesis of NPs of other metals and classes of materials.

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The edge effects on the melting process of hexagonal boron nitride (h-BN) are studied using molecular dynamics simulation. First, the free-standing h-BN configuration containing 10,000 atoms is studied with different armchair/zigzag edge ratios to see the influence of armchair and zigzag edges of the initial configuration on the phase transition process from a crystal to a liquid state. Then, the number of atoms in this critical armchair/zigzag ratio configuration increases to find the standard number of atoms in the initial configuration. Next, the atomic melting mechanism and the phase transition temperature from crystal to liquid of the critical initial free-standing h-BN configuration are studied. Following, the armchair h-BN nanoribbon is created from the critical initial free-standing h-BN configuration to study the melting process and the atomic melting mechanism from crystal to liquid. Finally, the edge effects on the melting process are shown.

Recently, conventional viscosifiers exhibit limited effectiveness under deep formations due to their poor salt tolerance and low thermal resistance. To address the limitations, a thermo-responsive macromonomer (DAM) consisting of N,N-diethylacrylamide and N,N'-methylenebisacrylamide was copolymerized with 2-acrylamido-2-methylpropane sulfonate and chemically modified nano-silica (N-np) to obtain an effective thermo-thickening/Nano-SiO₂ polymer composite (N-DPAM) via in-situ polymerization under optimal conditions. The molecular structure of N-DPAM was analyzed by FTIR and ¹H NMR, while rheological and rheometric responses under high temperature, salt dosages, and shear resistance were investigated. The rheometric results demonstrated that DPAM exhibits a viscosity increase of 235% from 65 to 160 °C, but rapidly decreased at 180 °C, whereas N-DPAM displayed stabilized thickening responses of 218% above 160 °C due to intercalation and self-assembly of N-np within the polymer matrix as temperature increases. The viscosity retention rate (VRR) at a high shear rate of 1021 s⁻¹ and 200 °C indicated that the solution viscosity of N-DPAM was observed at 55 mPa s, which is 13 times higher compared to DPAM solution at 4 mPa s. From the rheological results, the VRR of N-DPAM fluid observed at 68% was slightly lower than that of HE300 at 73%, a commercially available viscosity additive in a salt-free environment at 200 °C, but three times higher (63%) than HE300 (25%) in the salt-saturated environment (20% NaCl). Additionally, a study of N-DPAM fluid contaminated by shaly soil from Dagang Oilfield demonstrated excellent compatibility with a filtration control agent to control the viscosity and filtration volumes (< 10 mL) at 200 °C.

Graphical Abstract

Novel active polymeric nanocomposites based on triazole complexes with some transition metals, Ni (II), Fe (III), and Cu(II), were synthesized through in situ microemulsion polymerization of methyl methacrylate and hydroxypropyl methacrylate as biocompatible polymeric nanospheres. TEM images demonstrated that the nanocomposites have been successfully formed into nanosphere shapes. While TEM and FTIR reaffirmed the formed structure, TGA supported the thermal stability of the produced nanocomposite. Herein, characterization and a sensitive electrochemical sensor were constructed for the evaluation of peroxide oxidation detection using the prepared polymeric nanocomposites with the triazole complexes. The differently prepared nanocomposite-modified screen-printed electrode showed high sensitivity toward hydrogen peroxide detection with a linear range of 1–1000 µM and a lower detection limit of 0.015 µM, which can be applied in the enzymatic biosensor field. Finally, polymeric nanocomposites based on triazole complexes have good electrochemical properties, which can be attributed to this compound possessing two electrochemical active components and/or the nanosphere structure of the particles that can further improve the electrochemistry through the possible oxidation states and the synergistic effect.