High Nanoparticle Concentrations Research Articles

Thermophysical and Corrosion Inhibitor Evaluation of Graphene, Aluminum Nitride and Barium Titanate Nanolubricants

A newly developed kind of fluid known as nanolubricant is produced by dispersing nanometer-sized materials in base oil. The main issue with nanolubricant is particle stability, which occurs when nanoparticles aggregate due to van der Waals forces. The aim of the study is to evaluate the performance of graphene (GR), aluminium nitride (AlN), and barium titanate (BTO) nanolubricants at 0.05 and 0.1 vol. % concentrations. The stability was identified by using sedimentation photograph capturing method and zeta potential analysis, while KD2 Pro Analyzer was used to measure the thermal conductivity, and the effect of corrosion inhibitor evaluation was measured according to ASTM D130-19. The nanolubricants are prepared by two-step method and undergo ultrasonication process to ensure the nanoparticles are well dispersed in base oil. The results showed that nanolubricants containing 0.05 vol. % nanoparticles are more stable than 0.1 vol. % nanolubricants. Nanolubricants with 0.1 vol. % showed signs of instability based on low zeta potential values. This is due to the fact that the higher the concentration of nanoparticles, the closer the nanoparticles are to one another. This increased van der Waals attraction and potentially causing nanoparticle agglomeration. Improvement in thermal conductivity was obtained with high volume concentration of GR, AlN and BTO nanoparticles. All nanolubricants achieved an ASTM Standard D130 classification of 1a based on the Copper Strip Corrosion Test Standard (slight tarnish, slight colour change). As a result, it was discovered that all prepared samples are effective anticorrosion lubricating oil additives.

Synthesis and Characterization of ZnO Nanoparticles by Pulsed Laser Ablation in Liquid Using Different Wavelengths for Antibacterial Application

In this paper, the synthesis of colloidal solution of ZnO nanoparticles by PLAL using an Nd: YAG laser with 1064 nm and 532 nm wavelengths is described. The optical, morphological, structural, wettability and antibacterial activities were studied. The XRD analysis showed the hexagonal wurtzite structure while the UV-vis indicated the blue shift of the absorption peak due to the surface plasmon of the nanoparticle, which showed significant changes in color behavior. The FE-SEM revealed a uniformed spherical shape with a partial size range of 20.50–21.48 nm for ZnO at 1064 and 57.08–59.87 nm for ZnO at 532nm. Also, the concentration measurement indicated that the concentration of ZnO prepared at 1064 nm is 26.7 μg ml-1 and 63 μg ml-1 at 532 nm due to the relevance of high energy to the Zn plate and little distortion in the water and high absorption of short wavelength. Finally, the optical density of the antibacterial activity has been investigated, and both concentrations have good antibacterial activity at 12 h. The ZnO prepared at 532 nm has higher antibacterial activity because it has a high concentration of nanoparticles for both S. aureus and E. coli. Finally, the cell viability for ZnO synthesis with both 1064 nm and 532 nm indicates that this material has high biocompatibility and could be used for medical applications.

Entropy analysis of mixed convective electro-magnetohydrodynamic couple-stress hybrid nanofluid flow with variable electrical conductivity in a porous channel

The paper presents a novel study to examine the irreversibility of quadratically mixed convective electro-magnetohydrodynamic (EMHD) flow of a couple-stress hybrid nanofluid (CSHNF) with variable properties in a vertical porous channel. The channel walls are exposed to an applied electric field effect and a uniform transverse magnetic field. The hybrid nanofluid considered is an ethylene glycol (C 2 H 6 O 2) base mixed with multi-walled carbon nanotubes (MWCNT) and silver (Ag) nanoparticles (NPs), assuming the base fluid and nanoparticles to be in a state of thermal equilibrium following the Tiwari-Das nanofluid model. The potential applications of the study can be in microfluidics to nanofluidics, particularly in developing cooling technologies, EMHD pumps, high-end microelectromechanical systems (MEMS), and lab-on-a-chip (LOC) devices used in bioengineering. A constant pressure gradient acting in the flow direction and the buoyancy effect under the quadratic Boussinesq approximation drive the flow. The governing momentum and energy equations are nondimensionalized using pertinent dimensionless parameters and solved by the semi-analytical homotopy analysis method (HAM). The entropy generation and the Bejan numbers are derived to examine the irreversibilities in the system. To investigate the rate of shear stresses and heat transfer, skin friction coefficients and Nusselt numbers on the channel walls are determined. The analysis emphasizes the influence of nanoparticle concentration and electromagnetic field on the flow dynamics, temperature distribution, and system irreversibilities in the presence of porous media. It reveals the enhancement of fluid velocity and temperature degradation for higher concentrations. In contrast, both reduce for higher magnetic and electrical strength. With the enhancement of electrical joule heating and quadratic convection, a higher entropy generation rate is attained with a low rate of heat transfer irreversibility. However, it reduces with higher nanoparticle concentration, electrical strength, porosity, and variable electrical conductivity parameters under the dominance of heat transfer irreversibility.

Effect of wastewater containing mixture of nanoparticles on organic matter removal, power generation, and biofilm integrity in sediment microbial fuel cell

ABSTRACT Industrial wastewaters from the cosmetic industry contain high organic strength and mixture of nanoparticles (NPs). Sediment microbial fuel cell (MFC) is an emerging nature-based technology that can treat complex wastewaters. The aim of this study is to understand the effect of a binary mixture of zinc oxide (ZnO) and copper oxide (CuO) NPs (concentration: 1 + 1 and 10 + 10 mg/L) on the organic matter removal, power generation, and biofilm health of sediment MFCs after a long-term operation of 120 days. The high chemical oxygen demand (COD) removal (>95%) observed for all reactors signified the minimal impact of 10 mg/L NP mixture on treatment. The dissolved organic carbon (DOC) removal from the sediment was reduced by 8% due to NPs. NPs also led to 42.2% higher anode extracellular polymeric substances (EPS) and 46.65% lesser cathode EPS generation. The maximum power density of 0.29 mW/m2 was obtained for the 10 mg/L NP reactor, with the average being 23% higher than the no-NP control reactor. This was the first study to explore the effect of the mixture of NPs on the performance of an MFC. The results indicated that sediment MFCs can sustain high mixture concentrations of NPs. Furthermore, variation of parameters can aid in establishing the feasibility of this technology for treating wastewater with NPs.

A novel green nanocomposite for EOR: Experimental Investigation of IFT Reduction, wettability Shift, and nanofluid stability

A stable nanofluid (NF) is crucial for success of nano-enhanced oil recovery (nEOR) processes. However, this represents a significant challenge as nanoparticles (NPs) tend to agglomerate under high salinity and NP concentration adversely affecting the oil recovery. New nanomaterials including functionalized nanoparticles also known as nanocomposites (NC) can help to overcome these issues. In this paper, first, we reported synthesis, characterization, and performance evaluation of a novel hydrophobic CuO-SiO2-Montmorillonite-K+-Thiazine NC for the first time. The NC was characterized using Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDAX), X-Ray Diffraction (XRD), Thermogravimetry Analysis (TGA), and Fourier Transform Infrared Spectroscopy (FTIR). SEM analysis showed that the NC is composed of uniformly distributed NPs. EDAX results confirmed presence of Cu, SiO2, O2, and Cl in the NC. XRD analysis indicated that SiO2 is the dominant phase in the crystal lattice and responsible for adsorption capacity of the NC. TGA analysis showed that the NC will be thermally stable in typical reservoir temperatures (∼80°C). FTIR results confirmed presence of Si-O, Cu-O, Si-O-Si, Al-O-Si, Al-OH, and OH bonds in the NC. In the second phase of this research work, the novel NC was used to investigate recovery of a Kazakhstani paraffinic heavy crude oil from Berea sandstone with focus on IFT reduction, oil recovery, wettability alteration, and stability analysis of the NFs. NFs were prepared with NC concentrations of 250, 500, and 1,000 ppm using moderate salinity (MS), low salinity (LS), and distilled water (DW). The results showed that the optimal NF (250 ppm LS) exhibited a high zeta potential value (−65.5 mV) indicating a high stability which is superior to all of the previously reported NCs. This high stability is attributed to use of thaizine as a source of natural surfactant. The optimum NF also altered the wettability of the sandstone by 77.6% and the contact angle (CA) was reduced from 117.9° to 26.4° making the system strongly water wet. The nanoclay has significantly facilitated the wettability alteration. The optimum NF also reduced the IFT by 92.3% from 27.42 mN/m to 2.11 mN/m. An incremental oil recovery of 20% was also achieved in the tertiary or EOR stage of oil. A comparison with the NCs reported in the literature confirmed the excellent performance of this novel NC in terms of NF stability, IFT reduction, and wettability alteration. The novel NC has a great potential for nEOR and other oilfield and environmental applications.

Are Nanostructured Lipid Carriers (NLC) better than Solid Lipid Nanoparticles (SLN) for delivering abiraterone acetate through the gastrointestinal tract?

Abiraterone acetate (AbA) is a progesterone derivative indicated for the treatment of metastatic prostate cancer. This BCS (Biopharmaceutics Classification System) Class IV molecule has an extremely poor oral bioavailability (<10 %), notably due to its very low water solubility and intestinal permeability. Among the few existing galenic strategies to improve AbA’s oral bioavailability, lipid nanoparticles such as Solid Lipid Nanoparticles (SLN) and Nanostructured Lipid Carriers (NLC) are relevant nanovectors. The objective of this study is to develop and compare SLN and NLC for oral delivery of abiraterone acetate. Both SLN and NLC are biocompatible, biodegradable and produced by high pressure homogenization (HPH), an ecological-friendly manufacturing process, organic solvent-free and easily scalable. The HPH process allowed the formation of AbA-loaded SLN and NLC with particle size lower than 160 nm and high encapsulation efficiencies. The addition of a liquid lipid significantly reduced the mean diameter of the nanoparticles, reflecting the greater benefit of the NLC formulation compared to SLN. Both SLN and NLC formulations offered an important protection of AbA in intestinal media, with a better stability for NLC. When encapsulated in SLN or NLC, the AbA is strongly retained by the nanoparticles, whatever the dissolution medium, which means that both formulas are able to protect and retain the drug in the intestinal tract, right up to its delivery to the enterocytes surface. High concentrations of nanoparticles were administered without cytotoxicity, especially for the NLC, which provides a real added value in terms of biocompatibility with Caco-2 cells. Finally, the nanoparticles were able to penetrate into enterocytes by the transcellular route, demonstrating an intense cellular internalization.

Evaluation of extraction and storage conditions for quantification and characterization of silver nanoparticles in complex samples by single particle-ICP-MS

The extraction of nanoparticles (NPs) from complex matrices and subsequent storage can potentially alter the NPs physicochemical properties and hinder cross-study comparisons. Most NP extraction methods are designed and tested at high nanoparticle concentrations, although (eco)toxicological and regulatory monitoring programs require methods capable of analyzing NPs at environmentally relevant concentrations (lower ppb range). In this study, we investigated how extraction methods affect the characteristics of PVP coated and citrate-stabilized silver NPs (AgNPs) spiked into soil, sewage sludge, and biological samples at environmentally relevant concentrations using Single Particle Inductively Coupled Plasma Mass Spectrometry spICP-MS). Further we investigated the impact of storage temperature (-80°C to 21°C) and storage duration (1-28 days) on the particle characteristics such as particle size.We found that aqueous AgNPs samples with low ionic strength media retained their original characteristics (like particle size, particle concentration and particle-based Ag mass) when preserved at 4°C for up to 28 days. AgNPs dispersed in high ionic strength media were however better preserved at -80°C. Among the extraction agents, tetrasodium pyrophosphate was more efficient in extracting AgNPs from soil and sewage sludge matrices, while Proteinase K was more suitable for biological samples from organisms (earthworms or fish).Although our study focused only on AgNPs, it provides crucial information to aid interlaboratory comparisons and data interpretation for (eco)toxicological studies.

Experimental investigation of heat transfer enhancement, thermal efficiency, and pressure drop in forced convection of magnetic hybrid nanofluid (Fe₃O₄/TiO₂) under varied magnetic field strengths and waveforms

Applying a magnetic field to influence convective flow of ferrofluids has become an efficient method for enhancing heat transfer in thermal systems, particularly in straight tubes. This study investigates the heat transfer properties of Fe₃O₄/TiO₂ nanofluids within a heated copper tube under varied magnetic field strengths and waveforms. Optimal magnetic field conditions were determined at 4 V and 60 Hz across all waveform types, as higher frequencies and voltages increased magnetic field intensity, thereby reducing heat transfer rates. Magnetic waveforms exerted differential influences on pressure drop, indicating varied nanoparticle alignment and turbulence levels, impacting fluid flow dynamics and viscosity. Higher nanoparticle concentration (0.1% vol) correlated with increased pressure drops across sine, square, and triangular waveforms, suggesting heightened flow resistance and potential nanoparticle agglomeration, thus reducing thermal efficiency. Conversely, lower concentrations exhibited enhanced thermal performance due to improved nanoparticle dispersion and reduced thermal resistance. At 0.1% vol, heat transfer enhancement without a magnetic field was 16.5%. The introduction of magnetic field waveforms attenuated this enhancement: 15.3% (sine), 13.26% (square), and 12.59% (triangular). Conversely, at lower volume fractions, heat transfer enhancements with magnetic fields exceeded those without at 0.05% vol, enhancements were 20.92% (sine), 21.3% (square), and 21.34% (triangular); at 0.025% vol, enhancements were 22.07% (sine), 22.3% (square), and 21.32% (triangular); at 0.0125% vol, enhancements were 27.87% (sine), 28.21% (square), and 26.74% (triangular); and at 0.0065% vol, enhancements were 22.24% (sine), 22.3% (square), and 24.49% (triangular).

Influence of Silver Nanoparticle Integration on the Composition and Surface Properties of Acrylic Dental Resins Employed in Temporary Bridges

Background: Recognized widely for its irreversible effects, periodontal disease stands as one of the most prevalent conditions, particularly emphasizing the potential for permanent damage caused by gingivitis, extending to encompass the entirety of the supportive complex, including the connective tissue and alveolar bone. Patients necessitating comprehensive periodontal and prosthetic treatments require an interdisciplinary approach, involving the coordination of pre-treatment procedures and appropriate prosthetic strategies. The adoption of advanced materials and techniques can prove beneficial in addressing complex dental issues. (2) Methods: Forty specimens were prepared using the prescribed procedure, with 20 acting as controls and the other 20 integrating AgNPs. The initial step involved crafting wax patterns of distinct shapes: dumbbell shapes for tensile testing and rectangular shapes for roughness assessments. These dimensions were aligned with ASTM D-638 and ISO 527-2 standards and adjusted to match the specifications of the analysis device for mechanical properties. (3) Results: In this case, the results indicate minimal differences in heat-curing acrylic resins compared to the control samples at a 5% concentration. However, notable disparities arise at concentrations of 10% and 20%. (4) Conclusions: Temporary prosthetic constructions are essential for preventing functional imbalances and complications. Incorporating AgNPs at a 5% concentration maintains mechanical properties while providing antibacterial effects for long-term interim prosthodontic restorations. Higher nanoparticle concentrations may reduce resin mechanical properties without affecting material surface condition

Nanostructured materials as hazardous wastewater micropullutants: Sources, behavior, and impact on functional bacterial community of activated sludge

Unique properties of nanoscale materials make them attractive for industrial, medical, agricultural, and environmental applications. Nevertheless, the release of nanoparticles into the environment is a major concern due to the lack of knowledge about their behavior in the environment and potential widespread environmental impacts. On the one hand, nanomaterials are perceived as pollutants that may affect activated sludge microorganisms and, consequently, the efficiency of wastewater treatment processes. On the other hand, some nanomaterials can be intentionally added to activated sludge systems to improve their performance in terms of, e.g., sludge settling and removing heavy metals or organic pollutants. As a result, nanoparticles are frequently accumulated in wastewater, which is considered to be a major source of nanoparticle release to the surrounding environment. Processes that involve the action of activated sludge are used worldwide in wastewater treatment plants due to their excellent capacity of removing nutrients, degrading toxins, and retaining biomass. High concentrations of nanoparticles entering activated sludge systems can affect their growth and metabolism. The research studies, which are reviewed in the present article, show that nanoparticles significantly reduce the relative abundance of the activated sludge microbial community associated with nitrification, denitrification, and phosphorus removal. The knowledge about the structure of the activated sludge microbial community with an assessment of nanomaterial toxicity can contribute to optimizing the sludge population and improving the performance of wastewater treatment plants.

Evaluation of the Effects of High Silver and Copper Nanoparticle Concentrations on Vaccinium myrtillus L. under Field Conditions.

The extensive development of nanotechnologies has allowed nanoparticles to impact living systems through different pathways. The effect of single exposure to high concentrations of silver and copper nanoparticles (50-200 mg/L) on Vaccinium myrtillus L. under field conditions was investigated. Nanoparticle uptake in different segments of Vaccinium myrtillus L. was assessed by applying inductively coupled plasma-atomic emission spectroscopy and a particle-induced X-ray emission technique. Copper nanoparticles mainly accumulated in the roots and leaves, while silver nanoparticles showed a higher affinity for the roots and berries. The nanoparticles' effects on the pigments and antioxidant activity of the plant's leaves were also evaluated. The possible human health risk associated with the consumption of nanoparticle-contaminated berries was assessed. The results indicated that the consumption of berries contaminated with nanoparticles presented a low risk for human health.

Surfactant-Free Preparation of Conjugated Polymer Nanoparticles in Aqueous Dispersions Using Sulfate Functionalized Fluorene Monomers.

Conjugated polymer nanoparticles (CPNs) can be synthesized by a Suzuki-Miyaura cross-coupling miniemulsion polymerization to give stable dispersions with a high concentration of uniform nanoparticles. However, large amounts of added surfactants are required to stabilize the miniemulsion and prevent the aggregation of the nanoparticles. Removal of the excess surfactant is challenging, and residual surfactant in thin films deposited from these dispersions can reduce the performance of optoelectronic devices. We report a novel approach to prepare stable dispersions with no added surfactant using a fluorene monomer, 2,7-dibromo-9,9-bis(undecanesulfate)-9H-fluorene, with alkyl side chains terminated by negatively charged sulfate groups. This functionality mimics the structure of one of the most commonly used surfactants, sodium dodecyl sulfate (SDS). This charged monomer effectively stabilizes the miniemulsion through electrostatic repulsion without the use of any additional surfactant in molar ratios ranging from 2.0 to 20.0 mol % of total monomer content for the preparation of poly(9,9-dioctylfluorene) (PFO) and poly(9,9-dioctylfluorene-alt-bithiophene) (PF8T2). Incorporation of 5.0 mol % of the amphiphilic monomer gave stable dispersions with a surface potential below -40 mV and, and polymers with molar mass (Mn) above 10 kg mol-1. This method should be generally applicable to the preparation of dispersions of polyfluorenes for application in organic electronic and optoelectronic devices without the requirement for time-consuming processes to remove residual surfactant.

Green Synthesis of Iron Nanoparticles Using Spinacia oleracea and Their Role in Antioxidant Defence

The green synthesis of iron oxide nanoparticles (Fe2O3) using Spinacia oleracea leaf extract is explored in this study. Iron oxide nanoparticles are noted for their unique properties, such as enhanced chemical reactivity due to their high specific surface area to volume ratios. Unlike traditional physical and chemical methods, green synthesis presents an environmental friendly alternative, leveraging biological processes for nanoparticle production. This method is particularly significant due to its potential applications in various fields, including medicine, where iron nanoparticles demonstrate antibacterial activity. However, limited research exists on their antioxidant properties. In this research, Spinacia oleracea leaf extract is utilized to synthesize iron oxide nanoparticles, followed by characterization using UV-Visible spectroscopy, FTIR, XRD, and SEM techniques. The results underscore the necessity for further investigation into the impact of nanoparticles on biological processes and the long-term effects of high nanoparticle concentrations on ecological stability. Additionally, this study includes an evaluation of antioxidant properties of the nanoparticles to address gaps in current research. Key Words Green synthesis, iron oxide, ecological stability, antioxidant, biological, nanoparticles.

Enhancing the heat transfer in CuO-MWCNT oil hybrid nanofluid flow in a pipe

In this study, three-dimensional steady-state laminar flow simulations were conducted in a horizontal pipe using CuO and multi-walled carbon nanotubes (MWCNT) nanoparticles with engine oil as the base fluid. Various nanoparticle volume fractions were examined under a constant heat flux boundary condition applied to the pipe wall. The main goal was to assess and compare the effects of different nanoparticle volume concentrations, including CuO and MWCNT in ratios of 1:1 and 1:2, on convective heat transfer. A second-order discretisation method was employed for solving the equations, and the SIMPLE algorithm was used for pressure–velocity coupling in the CFD code. The study focused on the impact of nanoparticle volume fraction on the convective heat transfer coefficient and the Nusselt number at a Reynolds number of 750. The findings indicate that increasing the nanoparticle volume fraction enhances both the convective heat transfer coefficient and the Nusselt number, with MWCNT having a more pronounced effect compared to CuO. Specifically, adding 2% CuO increases the heat transfer coefficient by 65%, while a mixture of 1% CuO and 1% MWCNT boosts it by 75%. The thermal boundary layer thickness also grows with higher nanoparticle concentrations, with 1% CuO and 3% CuO increasing the thickness by 1.5% and 3.6%, respectively. A formula for the thermal boundary layer thickness in CuO-oil nanofluids is provided based on volume fraction, and a scale analysis of the average heat transfer coefficient confirms that the simulation results are consistent with this analysis.

Performance analysis of an Active Magnetic Regenerative system using Al2O3 nanofluids

This study investigates the utilization of Al2O3 nanofluids in an Active Magnetic Regenerative (AMR) system, focusing on varying nanoparticle concentrations from 0.01 to 1.0%. Numerical modelling is used to analyze the effects of nanoparticle incorporation on system efficiency and cooling performance. Al2O3 nanoparticles are found to significantly increase the thermal conductivity, density, and viscosity of the base fluid while reducing specific heat capacity. Comparative analysis reveals that Al2O3 nanofluids outperform pure water in terms of cooling performance, achieving a lower final temperature and a higher temperature span after 60 min of operation. Moreover, the study highlights that cooling capacity and pumping work increase with higher nanoparticle concentrations, with a notable improvement of 64.95% in cooling capacity and 39.31% in pumping work for the 1.0% Al2O3 nanofluid compared to water. The Coefficient of Performance (COP) of the AMR system peaks at an optimal nanoparticle concentration of 0.2%, reaching 3.88, before declining due to increased pumping power requirements.

Entrance process and interface distribution of nanoparticles in point contact

Nanoparticles have proven to be effective in reducing friction and wear in tribological systems. Previous research mainly focused on the behavior of nanoparticles within the contact region, often overlooking the dynamics of particle's ingress into the interface. This study introduces an innovative model to elucidate the entry process of particles in point contact, grounded in mechanical analysis. The model is employed to investigate the distribution and load-bearing capacity of nanoparticles within the interface, considering variables such as velocity, applied load, particle concentration, particle size, and friction coefficient. Relative ball-on-disk experiments were conducted to verify the model’s prediction, with particular attention to the elemental distribution of particles along the wear tracks. Both theoretical and experimental results indicate that the distribution of particles shifts from covering the whole contact interface to concentrating at the edge in the movement direction as the external load increases and the velocity decreases. Additionally, while the spatial distribution of particles remains constant, the particle concentration within the interface significantly increases with higher nanoparticle concentrations. The enhanced tribological performance of nanofluid is attributed to a greater number of particles entering the contact region.

Vat photopolymerization of silica reinforced styrene-butadiene rubber elastomeric nanocomposites

Compared to their unfilled counterparts, elastomeric nanocomposites offer tailorable combinations of properties, including improved mechanical properties, increased durability, and enhanced thermal and electrical conductivity. However, the high viscosity caused by the presence of both the high molecular weight elastomer and the inclusion of fillers complicates additive manufacturing (AM) of elastomeric nanocomposites. This is especially challenging in vat photopolymerization (VP) AM, which requires resins that possess low viscosity (< 10 Pa·s) and exhibit sufficient storage modulus (∼ 104 Pa) when photocured. To address this process limitation, the authors have previously demonstrated decoupling the relationship between viscosity and molecular weight via VP of a photocurable composite latex resin. In this approach, a photocurable matrix is photocured as a scaffold around the latex particles, which provides sufficient modulus for the printed "green" part. Following a dehydration post-processing step, the latex particles coalesce to provide the final elastomeric mechanical properties without compromising feature resolution.In this work, the authors explore the effects of the addition of silica nanoparticles (10, 15, and 20 wt.%) on (i) the printability of photocurable styrene-butadiene rubber (SBR) latex resin and (ii) the mechanical properties of the resultant printed composites. The printable photocurable silica-SBR colloidal resin is realized by balancing the viscosity of the resin, the modulus of the cured green body, the silica nanoparticles content for reinforcement, and the high SBR content for elastomeric behavior. Specifically, the photocurable colloidal resin's viscosity is controlled by formulation design, while high silica nanoparticle content in the final part is achieved through evaporation of unreactive diluent. Characterization of the printed SBR nanocomposites with 20 wt.% silica reinforcement elucidated significant enhancements in the tensile strength (53 % increase), Young's modulus (671 % increase), and Shore A hardness (108 % increase) compared to printed SBR without filler reinforcement. To the authors' knowledge, this is the first report of 3D printing rubber nanocomposite using VP.

Defect formation and growth in metal nanocomposites consisting of Cu nanoparticles embedded in Ni or Al coatings

Fully inorganic or metallic nanocomposite coatings are promising materials for various applications but face limitations in term of their synthesis. A complementary synthesis process, Physical Vapor Deposition combined with magnetron sputtering and plasma-assisted gas-phase aggregation produced Cu nanoparticles embedded in metallic matrix. In this study, the effect of embedded nanoparticles on the matrix structure was investigated. Al and Ni were selected as matrix materials due to their different sputter yields leading to different growth modes film morphologies and difference in surface energy. Depending on the nanocomposite and deposition conditions, defects such as nodular growth were occasionally observed. These growth anomalies originated from the presence of nanoparticles creating new nucleation points for the matrix to grow disturbing the grain growth around it. Key factors responsible for their formation include the surface energy difference between the NPs and the matrix and the geometrical disruption occurring for large NP. In extreme cases with a high concentration of nanoparticles, coatings entirely constituted of nodular defects were produced which can be advantageous for applications needing large specific surface area.

Flexible Scaffold Modulation of Spatial Structure and Function of Hierarchically Porous Nanoparticle@ZIF-8 Composites to Enhance Field Deployable Disease Diagnostics.

Catalytic nanoparticle@metal-organic framework (MOF) composites have attracted significant interest in point-of-care testing (POCT) owing to their prominent catalytic activity. However, the trade-off between high loading efficiency and high catalytic activity remains challenging because high concentrations of nanoparticles tend to cause the misjoining and collapse of the MOFs. Herein, a facile strategy is reported to encapsulate high concentrations of platinum (Pt) nanoparticles into zeolitic imidazolate framework-8 (ZIF-8) using polydopamine (PDA) as a support for Pt@ZIF-8 and as a flexible scaffold for further immobilization of Pt nanoparticles. The resulting composite (Pt@ZIF-8@PDA@Pt) exhibits ultrahigh Pt nanoparticle loading efficiency, exceptional catalytic activity, stability, and a bright colorimetric signal. Following integration with lateral flow immunoassay (LFIA), the detection limits for pre- and post-catalysis detection of B-type natriuretic peptide (NT-proBNP) are 0.18 and 0.015ng mL-1, respectively, representing a 6-fold and 70-fold improvement compared to gold nanoparticle-based LFIA. Moreover, Pt@ZIF-8@PDA@Pt-based LFIA achieves 100% diagnostic sensitivity for NT-proBNP in a cohort of 184 clinical samples.

Optimised stress – intensification of pyocyanin production with zinc oxide nanoparticles

BackgroundPyocyanin is a blue pigment produced by Pseudomonas aeruginosa. Due to its unique redox properties over the last decade, it has gained more and more interest as a utile chemical. Nevertheless, it remains a rather costly reagent. It was previously shown that the production of pyocyanin can be enhanced by employing various methods. Among them are using statistical methods for planning the experiments or exposing bacterial cultures to stressors such as nanoparticles dosed in sublethal concentrations, e.g. zinc oxide nanoparticles.ResultsThe Design of Experiment (DoE) methodology allowed for calculating the optimal process temperature and nanoparticle concentration to intensify pyocyanin production. Low concentrations of the nanoparticles (6.06 µg/mL) and a temperature of 32℃ enhanced pyocyanin production, whereas higher concentrations of nanoparticles (275.75 µg/mL) and higher temperature stimulated biomass production and caused the abolishment of pyocyanin production. Elevated pigment production in zinc oxide nanoparticles-supplemented media was sustained in the scaled-up culture. Conducted analyses confirmed that observed stimulation of pyocyanin production is followed by higher membrane potential, altered gene expression, generation of reactive oxygen species, and accumulation of zinc in the cell’s biomass.ConclusionsPyocyanin production can be steered using ZnO nanoparticles. Elevated production of pyocyanin due to exposure to nanoparticles is followed by the number of changes in physiology of bacteria and is a result of the cellular stress. We showed that the stress response of bacteria can be optimised using statistical methods and result in producing the desired metabolite more effectively.