Behavior Of Nanomaterials Research Articles

Simulating and Predicting Adsorption of Organic Pollutants onto Black Phosphorus Nanomaterials.

Layered black phosphorus (BP) has exhibited exciting application prospects in diverse fields. Adsorption of organics onto BP may influence environmental behavior and toxicities of both organic pollutants and BP nanomaterials. However, contributions of various intermolecular interactions to the adsorption remain unclear, and values of adsorption parameters such as adsorption energies (Ead) and adsorption equilibrium constants (K) are lacking. Herein, molecular dynamic (MD) and density functional theory (DFT) was adopted to calculate Ead and K values. The calculated Ead and K values for organics adsorbed onto graphene were compared with experimental ones, so as to confirm the reliability of the calculation methods. Polyparameter linear free energy relationship (pp-LFER) models on Ead and logK were developed to estimate contributions of different intermolecular interactions to the adsorption. The adsorption in the gaseous phase was found to be more favorable than in the aqueous phase, as the adsorbates need to overcome cohesive energies of water molecules onto BP. The affinity of the aromatics to BP was comparable to that of graphene. The pp-LFER models performed well for predicting the Ead and K values, with external explained variance ranging from 0.90 to 0.97, and can serve as effective tools to rank adsorption capacities of organics onto BP.

Behavior of two classes of organic contaminants in the presence of graphene oxide: Ecotoxicity, physicochemical characterization and theoretical calculations

Graphene oxide (GO) production has increased considerably and therefore its presence in the environment is inevitable. When in aquatic environment GO can interact with co-existing compounds, modifying their toxicities for several organisms. However, the toxic effects of co-exposure of GO and organic compounds are rarely reported in the literature. Herein, we studied the behavior of four organic aquatic contaminants found in surface water such as 2-phenylbenzotriazoles (non-Cl PBTA-9 and PBTA-9) and phenoxyphenyl pesticides, pyriproxyfen (PYR) and lambdacyhalothrin (LCT), in the presence of GO. GO reduced 90% and 83% of the toxicity of non-Cl PBTA-9 and PBTA for Daphnia. When PBTAs were adsorbed onto GO surface their interactions caused GO agglomeration (up to 20 mm) and consequent precipitation, making PBTAs less bioavailable. PYR and LCT's toxicities increased up to 83% for PYR and 47% for LCT in the presence of GO, because their adsorption on GO lead to the stabilization of the suspensions (up to 0.5 μm). Those particles were then easily ingested and retained in the digestive tract of the daphnids, triggering the Trojan horse effect. Based on theoretical calculations we observed that PBTA compounds are planar, electron-poorer and more reactive than the studied pesticides, suggesting a better stability of the GO/PBTA complexes. PYR and LCT are nonplanar, electron-richer and less reactive towards GO than PBTAs, forming less stable GO complexes that could facilitate the desorption of pesticides, increasing toxic effects. Our results suggest that the properties of the organic toxicants can influence the stability of graphene oxide suspensions, playing a fundamental role in the modulation of their toxicity. Further research is needed for a deep understanding of the behavior of nanomaterials in the presence of contaminants and their effect in the toxicity of aquatic organisms.

β-Cyclodextrin-Stabilized Biosynthesis Nanozyme for Dual Enzyme Mimicking and Fenton Reaction with a High Potential Anticancer Agent.

The myth of inactivity of inorganic materials in a biological system breaks down by the discovery of nanozymes. From this time, the nanozyme has attracted huge attention for its high durability, cost-effective production, and easy storage over the natural enzyme. Moreover, the multienzyme-mimicking activity of nanozymes can regulate the level of reactive oxygen species (ROS) in an intercellular system. ROS can be generated by peroxidase (POD), oxidase (OD), and Fenton-like catalytic reaction by a nanozyme which kills the cancer cells by oxidative stress; therefore, it is important in CDT (chemo dynamic therapy). Our current study designed to investigate the enzyme mimicking behavior and anticancer ability of cerium-based nanomaterials because the cerium-based materials offer a high redox ability while maintaining nontoxicity and high stability. Our group synthesized CeZrO4 nanoparticles by a green method using β-cyclodextrin as a stabilizer and neem leaf extract as a reducing agent, exhibiting POD- and OD-like dual enzyme activities. The best enzyme catalytic activity is shown in pH = 4, indicating the high ROS generation in an acidic medium (tumor microenvironment) which is also supported by the Fenton-like behavior of CeZrO4 nanoparticles. Inspired by the high ROS generation in vitro method, we investigated the disruption of human kidney cells by this nanoparticle, successfully verified by the MTT assay. The harmful effect of ROS in a normal cell is also investigated by the in vitro MTT assay. The results suggested that the appreciable anticancer activity with minimal side effects by this synthesized nanomaterial.

Theoretical Evaluation of Impact Characteristics of Wavy Graphene Sheets with Disclinations Formed by Origami and Kirigami.

Evaluation of impact characteristics of carbon nanomaterials is very important and helpful for their application in nanoelectromechanical systems (NEMS). Furthermore, disclination lattice defects can generate out-of-plane deformation to control the mechanical behavior of carbon nanomaterials. In this study, we design novel stable wavy graphene sheets (GSs) using a technique based on origami and kirigami to control the exchange of carbon atoms and generate appropriate disclinations. The impact characteristics of these GSs are evaluated using molecular dynamics (MD) simulation, and the accuracy of the simulation results is verified via a theoretical analysis based on continuum mechanics. In the impact tests, the C60 fullerene is employed as an impactor, and the effects of the different shapes of wavy GSs with different disclinations, different impact sites on the curved surface, and different impact velocities are examined to investigate the impact characteristics of the wavy GSs. We find that the newly designed wavy GSs increasingly resist the kinetic energy (KE) of the impactor as the disclination density is increased, and the estimated KE propagation patterns are significantly different from those of the ideal GS. Based on their enhanced performance in the impact tests, the wavy GSs possess excellent impact behavior, which should facilitate their potential application as high-impact-resistant components in advanced NEMS.

Deformation-Induced Phase Transformations in Gold Nanoribbons with the 4H Phase.

The mechanical stability of metallic nanomaterials has been intensively studied due to their unique structures and promising applications. Although extensive investigations have been carried out on the deformation behaviors of metallic nanomaterials, the atomic-scale deformation mechanism of metallic nanomaterials with unconventional hexagonal structures remains unclear because of the lack of direct experimental observation. Here, we conduct an atomic-resolution in situ tensile-straining transmission electron microscopy investigation on the deformation mechanism of gold nanoribbons with the 4H (hexagonal) phase. Our results reveal that plastic deformation in the 4H gold nanoribbons comprises three stages, in which both full and partial dislocations are involved. At the early deformation stage, plastic deformation is governed by full dislocation activities. Partial dislocations are subsequently activated in regions that have undergone full dislocation gliding, leading to phase transformation from the 4H phase to the face-centered cubic (FCC) phase. At the last stage of the deformation process, the volume fraction of the FCC phase increases, and full dislocation activities in the FCC regions also play an important role.

Human health risk factors associated with the application of nanomaterials : A review

During their application, behavior of nanomaterials can differ from the generally known, widely applied, considering their risks, familiar, legislated materials. Since they gained importance rapidly, we did not have enough time to study the mechanism of action of these materials in details. The short- and long-term effects of these materials are only scarcely known or not known. However, since the middle of the 2000s decade, an increasing trend can be noticed regarding the scientific literature dealing with the risk assessment of nanomaterials. It is important to pay special attention to the full life-cycle of the nanomaterials and to know the short- and long-term effects of some processes like mining, production, application, deposition, neutralization on our environment and on the health and security of the directly or indirectly affected people. In our paper we examine in detail the effects which can have an effect on human health and safety during the application of nanomaterials. We summarized the collected parameters to be tested, and we cathegorized them into topic areas in order to give assistance in the preparation risk assessments associated with nanomaterials, thus even the laymen can have a good overview on the critical factors in aspects of human health.

Rheological properties and mechanical characteristics analysis of nano-based cement plug

In the oil and gas industry, drilling is expensive, from the exploration phase through drilling and production to enhanced oil recovery. Therefore, it is important to maintain the integrity of the well till the end of the production phase. Cementing the wellbore during drilling helps to maintain the integrity of the well throughout its lifecycle. It is necessary to know the properties of the cement and the wellbore conditions before the cementing is done. Upon the addition of certain nanomaterial to the cement, the properties of the cement can be altered based on need. Use of nanotechnology in the cement slurry can help in achieving solutions to many problems that pertain to oil well cementation. This paper discusses the behavior of certain nanomaterials when added to cement at high temperatures and high pressures, and how the properties of cement are affected by the addition of these nanoparticles.

Heat Conduction Behavior of Two-Dimensional Nanomaterials and Their Interface Regulation※

Heat Conduction Behavior of Two-Dimensional Nanomaterials and Their Interface Regulation^※

Temperature and strain rate dependent tensile behavior of polycrystalline nanocopper under dynamic loading

In this work, thermomechanical response of polycrystalline nanocopper has been studied using molecular dynamic simulation in equilibrium conditions. The behavioral change of polycrystalline nanocopper has been studied at different strain rates i.e., 5 × 108 s−1, 1 × 109 s−1, 5 × 109 s−1, 1 × 1010 s−1 and 5 × 1010 s−1. The response of copper with increasing discrete temperatures from 100 K to 500 K, at steps of 100 K each, has also been analyzed. Embedded Atom Method (EAM) potential is used which governs the interaction amongst atoms and helps in finding out the positions of atoms using Newton’s second law of motion. Results have shown the dependency of Young’s modulus, yield strength, ultimate strength on strain rate and temperature. It has been observed that when the strain rate is increased, Young’s modulus also increases along with the increase in yield strength and ultimate strength. The Young’s modulus, yield strength, and ultimate strength show inverse relation with the increase in temperature. The results provide a base for further investigation of polycrystalline nanomaterials with effects of other parameters. The study may also be helpful for the researchers to predict the mechanical behavior of a polycrystalline nanomaterial under varying strain rate and temperature during its synthesis via bottom-up approach or surface modification.

Size and Shape dependence equation of state and bulk modulus for nanomaterials

A critical analysis of size and shape dependence properties of different type of nanomaterials is presented using a simple theory of equation of state (EOS) and bulk modulus. It is observed that compression behavior of nanomaterials depends on size and shape in addition to the applied pressure. To confirm the situation we have considered different type of nanomaterials. The model predictions are compared with the available experimental data. A good agreement between theory and experiments demonstrate the validity of model proposed for nanomaterials. Some results have also been reported in absence of experimental data to help the researcher engaged in the experimental studies of nanomaterials. Due to the simplicity and applicability of the model, it may be used to understand other properties of nanomaterials under varying physical conditions.

A study on structural analysis and magnetic behaviour of barium hexaferrite nanomaterial

A study on structural analysis and magnetic behaviour of barium hexaferrite nanomaterial

The effect of N-doping on the electronic structure property and the li and Na storage capacity of graphene nanomaterials: A first-principles study

We performed first-principles calculations to investigate the effect of N-doping on the electronic structure property and the Li/Na storage behaviors of graphene nanomaterials. Our calculations first revealed that the N-doping treatment can effectively increase the number of C vacancy defects in graphene and the adsorption energy of a Li/Na atom on C vacancy can be largely enhanced by increasing the pyridinic-/pyrrolic-N atoms at the vacancy site. However, the reversible Li/Na capacity of the C vacancy defect was found to be largely reduced by increasing the doping level of N, which was primarily determined by the electronic structure property of the N-doped graphene structures and their strong electrostatic interactions with Li/Na. Our results clearly revealed that the enhanced Li/Na capacity by the N-doping on the graphene surface can be primarily attributed to the induced formation of a great number of C vacancy defects rather than the presence of the pyridinic-/pyrrolic-N on the basal plane. Our calculations also showed that the pyridinic-N doped graphene edges can possess a Li/Na capacity comparable to that of the N-doped C vacancy defects. Nevertheless, this excess Li/Na capacity was found to be largely reduced by the termination of the H atoms on these edge pyridinic-N groups.

Thermodynamic patterns during in-situ heating of InAs nanowires encapsulated in Al2O3 shells

Understanding the dynamic thermal behavior of nanomaterials based on their unique physical and chemical properties is critical for their applications. In this study, the thermal behavior of single-crystalline InAs nanowires in an amorphous Al2O3 shell was investigated by conducting in situ heating experiments in a transmission electron microscope. Two different thermodynamic patterns were observed during the in situ heating experiments: (1) continuous vaporization and condensation simultaneously at temperatures lower than 838.15 K, and (2) pure evaporation at temperatures higher than 878.15 K. During the simultaneous condensation and vaporization in closer areas in a single InAs nanowire, the front edge of the vaporization was flat, while that of the condensation actively changed with time and temperature. Pure vaporization was conducted via layer-by-layer evaporation followed by three-dimensional vaporization at the final stage. The thermal behaviors of the InAs nanowires were demonstrated from a thermodynamic point of view.

Real-time visualization of morphology-dependent self-motion of hyaluronic acid nanomaterials in water

Drug delivery to target sites is often limited by inefficient particle transport through biological media. Herein, motion behaviors of spherical and nonspherical nanomaterials composed of hyaluronic acid were studied in water using real-time multiple particle tracking technology. The two types of nanomaterials have comparable surface compositions and surface potentials, and they have equivalent diameters. The analysis of nanomaterial trajectories revealed that particles with flattened morphology and a high aspect ratio, designated nanoplatelets, exhibited more linear trajectories and faster diffusion in water than nanospheres. Fitting the plots of mean square displacement vs. time scale suggests that nanoplatelets exhibited hyperdiffusive behavior, which is similar to the motion of living microorganisms. Furthermore, at 37 °C, the surface explored by a nanoplatelet was up to 33-fold higher than that explored by a nanosphere. This investigation on morphology-dependent self-motion of nanomaterials could have a significant impact on drug delivery applications by increasing particle transport through biological media.

Biodistribution of Quantum Dots-Labelled Halloysite Nanotubes: A Caenorhabditis elegans In Vivo Study.

Halloysite is a promising building block in nanoarchitectonics of functional materials, especially in the development of novel biomaterials and smart coatings. Understanding the behavior of materials produced using halloysite nanotubes within living organisms is essential for their safe applications. In this study, quantum dots of different compositions were synthesized on the surface of modified clay nanotubes, and the biodistribution of this hybrid material was monitored within Caenorhabditis elegans nematodes. The influence of the modification agent as well as the particles’ composition on physicochemical properties of hybrid nanomaterials was investigated. Several microscopy techniques, such as fluorescence and dark-field microscopy, were compared in monitoring the distribution of nanomaterials in nematodes’ organisms. The effects of QDs-halloysite composites on the nematodes’ life cycle were investigated in vivo. Our fluorescent hybrid probes induced no acute toxic effects in model organisms. The stable fluorescence and low toxicity towards the organisms suggest that the proposed synthesis procedure yields safe nanoarchitectonic materials that will be helpful in monitoring the behavior of nanomaterials inside living cells and organisms.

Surface and interface effects on the bending behavior of nonlinear multilayered magnetoelectric nanostructures

Surface effects have important influence on the magneto-electro-elastic behavior of nanomaterials, and interface effects have important influence on the bending of ME structures at the micron size and millimeter size. In this work, we introduce these two types of effects into Kirchhoff’s thin plate theory to study the nonlinear magneto-electro-elastic coupling of a multilayered magnetoelectric (ME) nanostructure. The layered structure is taken to consist of a nonlinear magnetostrictive material and a linear piezoelectric material with their magnetization and polarization directions pointing in the thickness direction. The governing equations of static bending of such multilayered nanostructures are derived, and analytical expressions of deflection under uniform magnetic field and external load are obtained. The influence of magnetic field on the deflection of ME circular-shaped multilayer nanostructure is studied. Finally, the influences of surface and interface effects, and of the applied electric potential and magnetic potential, on the bending characteristics of ME multilayer are analyzed. The obtained results could provide guidelines for the design and applications of various nano devices.

Three dimensional vectorial imaging of surface phonon polaritons

Surface phonon polaritons (SPhPs) are coupled photon-phonon excitations that emerge at the surfaces of nanostructured materials. Although they strongly influence the optical and thermal behavior of nanomaterials, no technique has been able to reveal the complete three-dimensional (3D) vectorial picture of their electromagnetic density of states. Using a highly monochromated electron beam in a scanning transmission electron microscope, we could visualize varying SPhP signatures from nanoscale MgO cubes as a function of the beam position, energy loss, and tilt angle. The SPhPs' response was described in terms of eigenmodes and used to tomographically reconstruct the phononic surface electromagnetic fields of the object. Such 3D information promises insights in nanoscale physical phenomena and is invaluable to the design and optimization of nanostructures for fascinating new uses.

A coarse-grained – Atomistic multi-scale method to study the mechanical behavior of heterogeneous FCC nano-materials

In this paper, a multi-scale method is developed to couple the atomistic domain with the coarse-grained system to model the mechanical properties of materials with defects and heterogeneity. The material properties are determined in the nano-scale level by Molecular Dynamics analysis, in which the interatomic potential is used to determine the interaction between the particles. The main issue with the Molecular Dynamics method is its high computational cost. Hence, the coarse-grained method is employed, where a number of atoms are assumed as a bigger bid, and the interatomic potential is modified in terms of the position of the grains. This method reduces the computational cost as the degrees of freedom decreases. Moreover, it has the advantage of using the same interatomic potential as molecular dynamics method comparing to the continuum-based approaches. One issue with the coarse-grained method is that phenomena with small wavelengths cannot be captured comparing to the all-atoms system. To this end, a multi-scale method is presented to couple the atomistic domain with the coarse-grained system. In this method, the regions near to the cracks, defects, or heterogeneity are modeled by the conventional MD scheme and farther regions by the coarse-grained method. In order to illustrate the capability of the proposed computational model, the evolution of misfit dislocation is investigated at the interface of Ni3Aland Ni, which is formed by their subtle difference in lattice parameter. Obviously, dislocations play a crucial role in determining the mechanical behavior of superalloys even though a considerable number of atoms are located in perfect lattice-structures, and dislocations comprise a small region of the domain. Thus, it is rational to apply the proposed CG–MD multi-scale method to study the mechanical behavior of such materials. Finally, the effect of loading and temperature is investigated on dislocation density of the Ni-based superalloys using the CG–MD multi-scale method; it is shown that dislocation density increases as the temperature or strain increases.

Two step synthesis and electrochemical behavior of SnO2 nanomaterials for electrical energy storage devices

Green mediated synthesis was employed to reduce the SnO2 nanomaterials from SnCl2 with the rhizome of Corallo carpus epigaeus as a reducing agent for the first time. The particles were subjected to optical, structural and morphological studies. In UV–Vis spectroscopy, the absorbent peak was observed at 352 nm confirmed the presence of Sn4+ ions. XRD pattern had been used to establish the tetragonal rutile structure of the nanomaterials. The morphological analysis revealed that the particles were in spherical shaped nanoclusters, with an average size of 10–11 nm. Electrochemical behavior was investigated using cyclic voltammetry method and electrochemical impedance spectroscopic studies. The response of CV curve was in quasi rectangular shape indicating the pseudo capacitive nature of the working electrode and also the behavior of reversible redox reactions. SnO2 nanomaterials exhibited larger specific capacitance value of 154.33 F/g at 5 mA/g. From the electrochemical impedance studies, the electron charge transfer resistance was observed to be 452 Ω which indicated significant capacitive performance of the SnO2 nanomaterials. The lower impedance generally indicate the enhanced performance of the energy storage device as well as improved electrons and diffusion of Sn4+ ions.

Insights into the transport of pristine and photoaged graphene oxide-hematite nanohybrids in saturated porous media: Impacts of XDLVO interactions and surface roughness

The transport behaviors of nanomaterials, in especial multifunctional nanohybrids have not been well disclosed until now. In this study, environmentally relevant conditions, including cation types, ionic strength and pH, were selected to investigate the transport and retention of graphene oxide-hematite (GO-Fe2O3) nanohybrids and a photoaged product in saturated sandy columns. Results show that more hybridization of hematite led to decreased negative surface charge, while increased particle size and hydrophobicity of the nanohybrids, which depressed their transport according to extented Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory. However, the inhibitory transport of photoaged nanohybrids was attributed to their distinct surface roughness caused by relatively high hybridization and photoirradiation. Notably the restrained transport was alleviated in the CaCl2 saturated media, since the less surface O-functional groups of the corresponding nanohybrids reduced the cation bridging effect caused by Ca2+. Similarly, increasing pH promoted the transport of the nanohybrids in NaCl saturated media, particularly for the nanohybrids that contained rich O-functional groups, but exerted inconspicuous effect on mobility of the nanohybrids in CaCl2 saturated media. These observations highlight that both XDLVO interactions and surface roughness may work together to impact the transport and fate of the burgeoning, versatile nanohybrids in the environment.