Low Nanoparticle Concentrations Research Articles

Comprehensive study of tri-hybrid nanofluid flow in a vertical channel with Cu, Al2O3, and TiO2 nanoparticles via fractional dynamics and non-local kernel approach

Nanofluids and hybrid nanofluids enhance the transfer of heat with low nanoparticle concentration. Tri-hybrid nanofluids combine different nanoparticles (NPs) to further increase the performance of base fluids. Tri-hybrid nanofluids have significant uses in several industries, including electronic cooling, heat transport, biomedical engineering as well as energy storage systems. This study investigates the thermal performance of tri-hybrid nanofluid in the existence of a magnetic field and porous saturated space along with copper (Cu), aluminium oxide (Al2O3), and titanium dioxide (TiO2) NPs dispersed in base fluid, i.e. water (H2O) flowing through a vertical channel by convection. The resultant partial differential equations based on Atangana–Baleanu time-fractional derivative (having non-singular and non-local kernel) are solved using the Laplace transform along with the appropriate physical conditions. The Stehfest as well as Tzou’s numerical approaches are then utilized to compute the Laplace inverse, to check the validity of obtained solutions and to get the graphical representations of, concentration, energy, and velocity fields. The results show that tri-hybrid nanofluids have advanced thermal as well as momentum characteristics compared to nanofluids and hybrid nanofluids.

Interplay between green-synthesized nanoparticles and plant performance is mediated by the microbial community in the rhizocompartments

Numerous green-synthesized nanoparticles are being evaluated for their potential application in soil, yet understanding their influence on plant performance and their rhizocompartments associated microbes is a gap that needs to be addressed. In this study, we investigated how applying iron oxide nanoparticles (control 0, low 25 and high 50 mg/kg) impacted the rhizocompartments associated microbial communities and plant secondary metabolites grown in natural soil microcosm. The transcriptional analysis showed that the majority of artemisinin and flavonoid biosynthetic pathway genes were significantly upregulated in plants with the application of low concentration of green-synthesized iron oxide nanoparticles (FeO.NPs) when compared with control plants, suggesting a fine collaboration between these metabolites’ pathways, as indicated by a remarkable increase in artemisinin content (2-fold), ferulic acid (7.6-fold), luteolin (4.3-fold) and syringic acid (6.2-fold). The response of rhizocompartments microbial communities and associated soil enzymes was investigated using high-throughput sequencing and profiler test kits, respectively. The soil microbial community structure was altered upon FeO.NPs exposure in both low and high treated soils as indicated by multivariate analysis. For instance, bacterial phyla Bacteroidetes and Gemmatimonadetes and fungal phyla Ascomycota demonstrated a significant rise in relative abundance in both the rhizosphere and rhizoplane in low and high treatments relative to the control. Moreover, genera level analysis revealed that Cupriavidus, Vibrionimonas, and Burkholderia displayed higher relative abundance (p < 0.05) in low FeO.NPs concentration while Giaella and Nonomuraea didn't show any noticeable response to FeO.NPs. In terms of fungal genera, Oidiodendron and Cryptococcus showed high relative abundance under low treatment. The altered microbiome profile is possibly associated with soil enzymes, for instance, urease and catalase activities were increased by 1.76 and 1.71-fold, respectively in low FeO.NPs. Thus, this study demonstrates the effects of FeO.NPs gradients on plant secondary metabolites and soil enzyme activities, while contributing new insights into their specific impacts on the microbial community composition in the rhizocompartments of plant root system.

Volatile carbonyl metabolites analysis of nanoparticle exposed lung cells in an organ-on-a-chip system

The evaluation of nanoparticles (NPs) cytotoxicity is crucial for advancing nanotechnology and assessing environmental pollution. However, existing methods for NPs cytotoxicity evaluation suffer from limited accuracy and inadequate information content. In the study, we developed a novel detection platform that enables the identification of cellular carbonyl metabolites at the organ level. The platform is integrated with a cell co-culture lung organ chip (LOC) and a micropillar concentrator. Notably, our work represents the successful measurement of the amounts of cellular metabolites on LOC system. The volatile carbonyl metabolites (VCMs) generated by cells exposure to various types of NPs with different concentrations were captured and detected by high-resolution mass spectrometry (MS). Compared with conventional cell viability and reactive oxygen species (ROS) analysis, our method discerns the toxicological impact of NPs at low concentrations by analyzed VCM at levels as low as ppb level. The LOC system based metabolic gas detection confirmed that low concentrations of NPs have a toxic effect on the cell model, which was not reflected in the fluorescence detection, and the effect of NP material is more significant than the size effect. Furthermore, this method can distinguish different NPs acting on cell models through cluster analysis of multiple VCMs.

Empirical investigation of the effect of adding nanoparticles to HB-80 gas turbine oil: Evaluation of thermophysical behaviors

The current study aims to conduct an empirical investigation on the performance of copper (II) oxide (CuO), Graphene Oxide (GO), and Molybdenum (VI) Oxide (MoO3) nanoparticles as additives for HB-80 base lubricant and their effects on essential characteristics such as density, flashpoint and flammability, cloud point and pour point, viscosity and viscosity indicators, thermal conductivity coefficient, friction coefficient and wear. The test results show that nanoparticles have minor effects on density and viscosity but managed to improve viscosity indicators. Flashpoint, flammability, cloud point, and pour point all increased after the addition of nanoparticles. The increase in the concentration of nanoparticles also improved and increased the lubricant's thermal conductivity coefficient; the highest increase was 11.3 % compared to the base oil with the addition of 1 wt% CuO. Adding nanoparticles to lubricant decreases wear and friction coefficient by creating a lubricant film, especially at lower nanoparticle concentrations, which leads to a more stable lubricant film by nanoparticles. Copper (II) Oxide nanoparticles had the best performance in reducing friction coefficient and wear at 0.2 wt% with 22.86 % and 63.92 % reduction compared to the base oil, respectively.

Electric partial discharges in biodegradable oil-based ferrofluids: A study on effects of magnetic field and nanoparticle concentration

This paper presents an experimental study of partial discharge activity in ferrofluids based on biodegradable transformer oil and iron oxide nanoparticles. Three ferrofluid samples with low, medium and high nanoparticle concentrations are employed in the research. The basic ferrofluid characterization is followed by a partial discharge experiment exposing the ferrofluids to a high voltage in a needle-plate electrode configuration. The analysis confirms that the apparent charge and number of discharges decrease with increasing nanoparticle concentration. These findings are interpreted with reference to the well-recognised electro-hydrodynamic streamer model. The charge trapping by nanoparticles hinders the ionization and discharge development. The study also focuses on the partial discharge activity in the ferrofluids under the action of a static magnetic field acting perpendicularly to the electric field. A decreasing trend in the number of discharges due to the magnetic field is revealed. A qualitative explanation is provided based on the field-induced cluster formation and charge mobility reduction. The presented experiment and the discussed findings may be valuable for practical application of the ferrofluid in high voltage equipment with a special need for partial discharge suppression.

Development of numerical code for mathematical simulating of unsteady solidification phenomena in existence of nanomaterial

This research zeroes in on improving the freezing process by synergistically employing a wavy wall and fins. To enhance cold penetration, the phase change material (PCM) is enriched with nanoparticles, and a single-phase model is adopted due to the low nanoparticle concentration. The numerical simulations leverage the Galerkin method and the validation procedure affirms the precision of the code, extensively evaluating the impacts of φ (concentration of additives) and dp (particle diameter). With an increase in particle diameter (dp), there is an initial 19.76% decrease in the required time, succeeded by a subsequent 50.56% increase when φ = 0.04. Furthermore, an escalation in φ results in an 11.04%, 40.91%, and 26.36% reduction in completion time for dp values of 50, 40, and 30 nm, respectively. Without the inclusion of powders, the solidification process lasts for 84.8 s. However, with the introduction of the optimal powder size, this duration significantly reduces to 50.1 s. This emphasizes the efficiency improvements attained through the strategic integration of a wavy wall, fins, and PCM infused with nanoparticles.

Revisiting thermo-physical property models of Al2O3-Water nanofluid for natural convective flow

One of the comprehensive ways of heat transport performance augmentation of thermo-fluid systems is to use nanofluid over base fluid. This study mainly scrutinizes several existing models of thermal conduction coefficient and absolute viscosity of Al2O3-water nanofluid with the experimental data. A benchmark problem of natural convective flow is selected to test the performance of the available nanofluid models. The Rayleigh number varies between 103 and 109, while the solid-volume proportion (φ) changes from 0 to 4%. The governing mathematical model is numerically discretized via the Galerkin finite element procedure under appropriate auxiliary conditions. The results produced by the models are verified with the existing experimental findings based on the evaluation of the Prandtl number and average Nusselt number. It has been confirmed that the AH model (Azmi's viscosity and Ho's conductivity models) is suitable for lower nanoparticle concentration (φ = 0.01), the AM model (Azmi's viscosity and Maxwell's conductivity models) for moderate concentration (0.01 < φ < 0.04), and the NH model (Ngueyn's viscosity and Ho's conductivity models) for higher value of the solid-volume proportion (φ = 0.04).

Fe-carbide/Fe-oxide-based nanocomposites synthesized as magnetic nanomaterials via laser ablation synthesis in solution (LASiS)

Magnetic nanostructured materials (MNMs) have gained prominence in materials technology developments owing to their potential biomedical applications for hyperthermia cancer treatment, and transplant organ cryopreservation. Herein, we report the facile and cost-effective synthesis of Fe-based composite MNMs, comprising both Fe@Fe2O3 and Fe3C@C core-shell nanoparticles (NPs), via Laser Ablation Synthesis in Solution (LASiS) using Fe targets ablated under acetone and toluene. Detailed materials characterizations using electron microscopy-based imaging, diffraction studies, and spectroscopic analyses - including Raman and Mössbauer spectroscopy - relate the structure-composition properties for different Fe-oxide/carbide phases in the aforesaid MNMs to their respective magnetic responses. Specifically, we confirm the presence of ultra-small (2–10 nm) amorphous Fe-oxide NPs, as well as Fe@Fe2O3 core-shell NPs (20–40 nm) in the samples synthesized by ablating Fe under acetone. In contrast, samples synthesized under toluene indicate a higher concentration of Fe3C@C core-shell NPs (20–40 nm) with a relatively low concentration of Fe2O3 NPs (2–10 nm). Furthermore, the crystallinity of the metallic phases and carbonaceous shell coatings are systematically increased by carrying out LASiS under heated toluene (up to ∼95 °C). Mössbauer spectroscopy results indicate that the elevation in toluene temperature leads to an increase in the concentrations of Fe3C@C NPs from ∼40 % to ∼53 % (at.).

Low Concentrations of Gold Nanoparticles as Electric Charge Carriers in Piezoelectric Cement-Based Materials.

Piezoelectric cement-based composites could serve to monitor the strain state of structural elements or act as self-powered materials in structural health monitoring (SHM) applications. The incorporation of piezoelectric materials as an active phase within cement matrices has presented a highly attractive avenue until today. However, their application is challenged by the low electrical conductivity of the hydrated cement matrix. Gold nanoparticles (Au NPs) possess substantial potential for elevating the free electrical charge within the matrix, increasing its electrical conductivity between the Au NPs and the cement matrix, thereby enhancing the piezoelectric response of the composite. In this sense, the objective of this study is to investigate the effects of incorporating low concentrations of gold nanoparticles (Au NPs) (442 and 658 ppm) on the electrical and piezoelectric properties of cement-based composites. Additionally, this study considers the effects of such properties when the material is cured under a constant electric field. Electrical impedance spectroscopy was used to evaluate the polarization resistance and piezoresistive properties of the material. Additionally, open-circuit potential measurements were taken alongside the application of mechanical loads to assess the piezoelectric activity of the composites. The findings revealed a notable decrease in the composite's total electrical resistance, reaching a value of 1.5 ± 0.2 kΩ, almost four times lower than the reference specimens. In the realm of piezoelectricity, the piezoelectric voltage parameter g33 exhibited a remarkable advancement, improving by a factor of 57 when compared to reference specimens. This significant enhancement can be attributed to both the concentration of Au NPs and the electrical curing process. In summary, the outcomes of this study underscore the feasibility of creating a highly electrically conductive cement-based matrix, using low concentrations of gold nanoparticles as electric charge carries, and indicate the possible piezoelectric behavior of the studied compposite.

Laser-Induced Intracellular Delivery: Exploiting Gold-Coated Spiky Polymeric Nanoparticles and Gold Nanorods under Near-Infrared Pulses for Single-Cell Nano-Photon-Poration.

This study explores the potential of laser-induced nano-photon-poration as a non-invasive technique for the intracellular delivery of micro/macromolecules at the single-cell level. This research proposes the utilization of gold-coated spiky polymeric nanoparticles (Au-PNPs) and gold nanorods (GNRs) to achieve efficient intracellular micro/macromolecule delivery at the single-cell level. By shifting the operating wavelength towards the near-infrared (NIR) range, the intracellular delivery efficiency and viability of Au-PNP-mediated photon-poration are compared to those using GNR-mediated intracellular delivery. Employing Au-PNPs as mediators in conjunction with nanosecond-pulsed lasers, a highly efficient intracellular delivery, while preserving high cell viability, is demonstrated. Laser pulses directed at Au-PNPs generate over a hundred hot spots per particle through plasmon resonance, facilitating the formation of photothermal vapor nanobubbles (PVNBs). These PVNBs create transient pores, enabling the gentle transfer of cargo from the extracellular to the intracellular milieu, without inducing deleterious effects in the cells. The optimization of wavelengths in the NIR region, coupled with low laser fluence (27 mJ/cm2) and nanoparticle concentrations (34 µg/mL), achieves outstanding delivery efficiencies (96%) and maintains high cell viability (up to 99%) across the various cell types, including cancer and neuronal cells. Importantly, sustained high cell viability (90-95%) is observed even 48 h post laser exposure. This innovative development holds considerable promise for diverse applications, encompassing drug delivery, gene therapy, and regenerative medicine. This study underscores the efficiency and versatility of the proposed technique, positioning it as a valuable tool for advancing intracellular delivery strategies in biomedical applications.

Encapsulated Rose Bengal Enhances the Photodynamic Treatment of Triple-Negative Breast Cancer Cells.

Among breast cancer subtypes, triple-negative breast cancer stands out as the most aggressive, with patients facing a 40% mortality rate within the initial five years. The limited treatment options and unfavourable prognosis for triple-negative patients necessitate the development of novel therapeutic strategies. Photodynamic therapy (PDT) is an alternative treatment that can effectively target triple-negative neoplastic cells such as MDA-MB-231. In this in vitro study, we conducted a comparative analysis of the PDT killing rate of unbound Rose Bengal (RB) in solution versus RB-encapsulated chitosan nanoparticles to determine the most effective approach for inducing cytotoxicity at low laser powers (90 mW, 50 mW, 25 mW and 10 mW) and RB concentrations (50 µg/mL, 25 µg/mL, 10 µg/mL and 5 µg/mL). Intracellular singlet oxygen production and cell uptake were also determined for both treatment modalities. Dark toxicity was also assessed for normal breast cells. Despite the low laser power and concentration of nanoparticles (10 mW and 5 µg/mL), MDA-MB-231 cells experienced a substantial reduction in viability (8 ± 1%) compared to those treated with RB solution (38 ± 10%). RB nanoparticles demonstrated higher singlet oxygen production and greater uptake by cancer cells than RB solutions. Moreover, RB nanoparticles display strong cytocompatibility with normal breast cells (MCF-10A). The low activation threshold may be a crucial advantage for specifically targeting malignant cells in deep tissues.

Multi-parameter study and two-step optimization of the nanofluid-filtered photovoltaic/thermal systems

Optimizing nanofluid filters and operational parameters is instrumental in enhancing the performance of nanofluid-filtered photovoltaic/thermal (PV/T) systems. However, studies on optimization of nanofluid-filtered PV/T systems have not yet been thoroughly explored. This work aims to optimize performance of nanofluid-filtered PV/T systems through a two-step procedure. Various scenarios of nanofluids tailored for specific solar cells were considered, and optimization was conducted based on the merit function (MF) to identify the most effective nanofluid filters parameters. The results showed that the optimization program tends to achieve satisfactory photovoltaic efficiency by combing a low nanoparticle concentration with a high optical path. A numerical model of the PV/T system was then developed to obtain the constraints of the operating parameters, which are used to optimize the system energy efficiency and exergy efficiency by genetic algorithm. The results demonstrated all systems present the satisfactory energy efficiency (>84 %) and exergy efficiency (>23 %). Specifically, the blended nanofluid-filtered PVSC-system achieved the highest energy efficiency of 89.45 %, while the GaAs-system with a single nanofluid filter attained the highest exergy efficiency of 27.90 %. This work contributes to advancing solar-to-PV/T efficiency, confirming the viability of blended nanofluid filters, and offering valuable insights for the development of nanofluid optical filters.

Seed nano-priming with multiple nanoparticles enhanced the growth parameters of lettuce and mitigated cadmium (Cd) bio-toxicity: An advanced technique for remediation of Cd contaminated environments

Seed nano-priming can be used as an advanced technology for enhancing seed germination, plant growth, and crop productivity; however, the potential role of seed nano-priming in ameliorative cadmium (Cd) bio-toxicity under Cd stress has not yet been sufficiently investigated. Therefore, in this study we investigated the beneficial impacts of seed priming with low (L) and high (H) concentrations of nanoparticles including nSiO2 (50/100 mg L−1), nTiO2 (20/60 mg L−1), nZnO (50/100 mg L−1), nFe3O4 (100/200 mg L−1), nCuO (50/100 mg L−1), and nCeO2 (50/100 mg L−1) on lettuce growth and antioxidant enzyme activities aiming to assess their efficacy for enhancing plant growth and reducing Cd phytotoxicity. The results showed a significant increase in plant growth, biomass production, antioxidant enzyme activities, and photosynthetic efficiency in lettuce treated with nano-primed nSiH + Cd (100 mg L−1), nTiH + Cd (60 mg L−1), and nZnL + Cd (50 mg L−1) under Cd stress. Moreover, nano-priming effectively reduced the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA) in lettuce shoots. Interestingly, nano-primed nSiH + Cd, nTiH + Cd, and nZnL + Cd demonstrated efficient reduction of Cd uptake, less translocation factor of Cd with high tolerance index, ultimately reducing toxicity by stabilizing the root morphology and superior accumulation of critical nutrients (K, Mg, Ca, Fe, and Zn). Thus, this study provides the first evidence of alleviating Cd toxicity in lettuce by using multiple nanoparticles via priming strategy. The findings highlight the potential of nanoparticles (Si, Zn, and Ti) as stress mitigation agents for improved crop growth and yield in Cd contaminated areas, thereby offering a promising and advanced approach for remediation of Cd contaminated environments.

Single domain soft ferromagnetic ferrofluid suitable for intratumoural magnetic hyperthermia

Magnetic hyperthermia is an effective modality for treating cancerous cells selectively at the intracellular level via proper administration, surface tagging and appropriate choice of magnetic nanoparticle. Also, achieving the therapeutic temperature with as much low concentration of nanoparticles, as possible, is desirable. Recently, ferromagnetic nanoparticles or ferrofluid are gaining attention as effective magnetic hyperthermia agents due to their enhanced heating potential under in vivo conditions. In the present work, we have fabricated citrate capped cobalt ferrite ferrofluid via a simple two-step process and investigated the physicochemical, magnetic and induction heating performance. The average size of the synthesized nanoparticle is 9 ± 4.3 nm which is suitable for intracellular hyperthermia and has the advantage that it can be easily eliminated from the body through renal clearance. The M(T) measurement of the ferrofluid confirmed the soft ferromagnetic behavior. The induction heating potential of the ferrofluid prepared was tested at different concentrations (1, 2, 5 & 10 mg/ml), suspension medium and alternating magnetic fields (15, 30 & 45 kA/m) with a fixed frequency of 316 kHz. Under a viscous environment, 1 mg/ml sample subjected to 45 kA/m reached the hyperthermia temperature within 160 s and the specific loss power was found to be 297 W/g(Co+Fe). Hence, the synthesized ferrofluid is suitable for intratumoural hyperthermia.

Low concentrations of selenium nanoparticles enhance the performance of a generalist parasitoid and its host, with no net effect on host suppression.

The environmental and economic costs of conventional insecticides have stirred an interest in alternative management tactics, including the use of nanotechnologies. Selenium nanoparticles (SeNPs) have many applications in agriculture but may not be compatible with biological control; however, low concentrations of SeNPs may benefit natural enemies via hormesis. This study investigates the concentration-dependent effects of SeNPs (0-1000 mg L-1 ) on Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae), a generalist parasitoid of stored product pests. The LC50 of SeNPs was 1540 mg L-1 for female parasitoids and 1164 mg L-1 for males. SeNPs had a significant hormetic effect; average lifespan increased by 10% at a concentration of 4.03 mg L-1 for females and by 35% at 13.83 mg L-1 for males. In a bioassay including hosts [the azuki bean beetle, Callosobruchus chinensis (L.) (Coleoptera: Chrysomelidae: Bruchinae)], a low concentration of SeNPs (25 mg L-1 ) enhanced the performance of female parasitoids; lifespan increased by 23% and the number of offspring increased by 88%. However, the number of emerging hosts did not significantly decrease; in the absence of parasitism, SeNPs actually improved host emergence by 17%. Because higher concentrations of SeNPs reduced parasitoid lifespan, whereas low concentrations enhanced not only parasitoid performance but also host emergence, practitioners should exercise caution when considering SeNPs for use in integrated pest management. © 2023 Society of Chemical Industry.

Exploration of nonlinear radiative heat energy on Buongiorno modeled nano liquid toward an inclined porous plate with heat source and variable chemical reaction

Nanofluids are fluid suspensions of nanoparticles that exhibit a considerable improvement in their characteristics at low nanoparticle concentrations. Numerous research on nanofluids focuses on interpreting their behavior in order to use them in applications where improving straight heat transmission is crucial, such as in various industrial settings, nuclear reactors, transportation, biology, food, and electronics. Thus, this study examines the implementation of a novel numerical technique, namely the shooting method for nonlinear radiative heat energy study on Buongiorno modeled nano liquid confined by an inclined porous plate. The Brownian and thermophoresis diffusions impacts are also accounted. The transmission of thermal and solutal energy is regulated by the considerable influence of nonlinear thermal radiation, heat source, and variable chemical reactions. The dimensional modeled partial differential equations (PDEs), by using precise similarity functions, have been mutated into ordinary differential equations (ODEs). The outcomes for the flow field, thermal, and solutal outlines are captured graphically. The values of the dimensionless parameters are chosen from the literature in such a way that they have significantly affected the dimensionless boundary layer (BL) profiles. Also, the non-dimensional profiles of velocity, temperature, and concentration observe two different trends (increasing and decreasing) for diverse values of the dimensionless parameters.

Non-Einsteinian viscosity reduction in boron nitride nanotube nanofluids

(1) Introduction: Nanoparticles have multiple applications, including drug delivery systems, biosensors, and carbon capture. Non-Einstein-like viscosity reduction has been reported in nanoparticle-polymer blends at low nanoparticle concentrations. More recently, a similar non-Einsteinian viscosity reduction effect has been observed in aqueous ultra-low concentration carbon-based nanofluids. (2) Methods: This work used a boron nitride nanotube functionalized with hydrophilic groups in rheological experiments to investigate the viscosity reduction in ultra-low concentration nanofluids (0.1-10 ppm). The dynamic viscosity was measured in an air atmosphere and methane (0-5 MPag) at low temperatures (0-10 C). (3) Results: A negligible effect on the temperature dependence of viscosity was found. Ultra-low concentrations of BNNT reduced the viscosity of the nanofluid by up to 29% at 10 ppm in the presence of methane. The results presented here were compared to similar studies on O-GNF and O-MWCNT nanofluids, which also reported significant viscosity reductions. (4) Conclusions: This work identified a non-Einsteinian viscosity reduction in BNNT nanofluids, which was exacerbated by methane dissolved in the nanofluid.

Toxic effects and mechanisms of engineered nanoparticles and nanoplastics on lettuce (Lactuca sativa L.)

Engineered nanoparticles (ENPs) and nanoplastics (NPs) are typical nanoparticles in terrestrial environments. Till now, few studies have compared their toxicity and mechanism to plants. Here we investigated the effects of CuO, nZVI ENPs and polystyrene (PS) NPs on lettuce growth, metabolic functions, and microbial community structure. Results showed that low concentrations of nanoparticles decreased root biomass and promoted photosynthetic indicators, whereas increased reactive oxygen species (ROS) were detected in roots exposed to high concentrations of nanoparticles. High-dose CuO ENP exposure significantly raised the MDA content by 124.6 % compared to CK, causing the most severe membrane damage in the roots among the three types of nanoparticles. Although linoleic acid metabolism was down-regulated, the roots alleviated CuO stress by up-regulating galactose metabolism. Uptake of PS by roots similarly caused ROS production and activated the oxidative stress system by altering amino acid and vitamin metabolism. Faster microbial responses to nanoparticles were observed in the nZVI and PS networks. The root toxicity was indirectly mediated by ion release, NP uptake, or ROS generation, ultimately impacting root cell metabolism, rhizospheric microorganism and plant growth. These findings provide theoretical basis for assessing environmental impact of nanoparticles and their possible ecological risks.

Electrophysical properties of laser-structured carbon nanomaterials functionalized with LaB6 nanoparticles

In this paper, we perform density functional theory (DFT)-calculations to study the effect of LaB6 nanoparticles on the electrophysical properties of carbon nanomaterial based on laser-structured multi-walled carbon nanotubes (MWCNTs). Based on the calculation results, the most energetically favorable landing sites for LaB6 nanoparticles on the surface of the carbon framework are determined. It is found that during the functionalization with LaB6 nanoparticles, the carbon framework takes on a charge from the atoms of lanthanum and boron, which leads to an increase in the density of electronic states of the MWCNT nanostructure. It is shown that even at low concentrations of LaB6 nanoparticles (4.5 %), the work function of the carbon nanomaterial decreases by 0.5 eV. The results of the calculations are verified in the course of a real experiment. To carry it out, using the original technology of laser irradiation, a hybrid nanomaterial was created from a vertical array of MWCNTs functionalized with LaB6 nanoparticles. Pulsed laser action on an array of MWCNTs with an adjusted energy density of 0.15 J/cm2 made it possible to shorten, align, and orient the upper ends of the nanotubes perpendicular to the substrate. The effect of binding of LaB6 nanoparticles to a carbon surface has been experimentally established. Laser exposure of the MWCNT array coated with LaB6 nanoparticles resulted in a ∼ 5 by times increase in electrical conductivity compared to the original MWCNT array. Recording the emission current-voltage characteristics of hybrid nanomaterials demonstrated a decrease in the total work function of the carbon nanomaterial after functionalization with LaB6 nanoparticles by 16 %. Field emission current density values were calculated for all samples based on their measured field emission CVC characteristics. The MWCNT array exhibited the highest current density of 0.37 A/cm2 after LaB6 deposition and laser exposure. It is predicted that the carbon nanomaterial based on laser-structured MWCNTs coated with LaB6 nanoparticles will be an excellent nanomaterial for field emission electronics.

Synergistic effects between anionic surfactant SDS and hydrophilic silica nanoparticles in improving foam performance for foam flooding

In foam flooding, foams stabilized by conventional anionic surfactants are usually raptured in contacting with crude oil, which behaves as a strong defoamer. In this article the synergistic effects between anionic surfactant SDS and negatively charged hydrophilic silica nanoparticles in stabilization of aqueous foams were examined. The results show that in either deionized (DI) water at 25 °C or Daqing simulated connate (SC) water with a total salinity of 6,778 mg/L at 45 °C, in absence of oil adding low concentration of silica nanoparticles into the SDS aqueous solutions can improve the foam performance of SDS mainly by increasing foam stability, as indicated by a synergistic effect index Se(d/s) (ratio of the composite foaming index of dispersion to that of solution) of 2.7 to 2.8. In presence of oil the foam performance of SDS in SC water at 45 °C can still be improved as indicated by an increased Se(d/s) of 3.7, but the maximum composite forming index is catastrophically reduced from 3222 Ls in absence of oil to 470 Ls in presence of oil. As similarly charged nanoparticles the silica nanoparticles do not adsorb at gas/liquid or oil/water interface to stabilize Pickering foams or Pickering emulsions but can improve emulsification of the oil, and the emulsified oil droplets together with the silica nanoparticles distribute in aqueous lamellae enhancing liquid viscosity and slowing down the liquid drainage in the foams. However, this effect weakens at high surfactant concentration, and addition of silica nanoparticles does not significantly reduce the interfacial tensions involved. The Enter (E), Spreading (S) and Bridging (B) coefficients of the oil in the foam systems are therefore still positive. The defoaming action of the oil in this system is not eliminated by only partially inhibited by addition of silica nanoparticles.