Addition Of Silica Nanoparticles Research Articles

The Addition of Silica Nanoparticles to Type IV Dental Stone: Influence on the Diagonal Tensile Strength

Introduction: Various methods have been studied to improve the properties of dental stones; one of them is adding nanoparticles to dental stones. In this study, the effect of adding different percentages of silica nanoparticles (0.5, 1, 2, and 5) on the diagonal tensile strength of dental stone type IV was investigated. Materials and Methods: Silica nanoparticles with percentages of 0.5, 1, 2 and 5 physically were mixed with dental stone type IV and then with distilled water according to the factory's instructions (23 ml to 100 g at 23°C). The diagonal tensile strength was measured using a Universal Testing Machine. In order to compare the diagonal tensile strength in different groups, ONE WAY ANOVA test and SPSS.26 software were used. The significance level was considered 0.05. Results: The addition of silica nanoparticles to dental stone type IV had no effects on the diagonal tensile strength of this material (P = 0.237). Conclusion: It can be concluded that adding silica nanoparticles does not negatively affect the diagonal tensile strength, and all concentrations performed similarly. This suggests that any of these concentrations can be used without concern for changes in tensile strength. However, further investigation is needed to evaluate the impact on other properties.

Damping and acoustic properties of nanosilica filled poly(styrene-acrylate) interpenetrating polymer networks (IPNs): Effect of nanocomposite preparation method

Research on noise pollution reduction has focused on utilizing damping coatings and polymer nanocomposites to enhance sound absorption. Nanosilica/poly(styrene-acrylate) nanocomposites as a water-based coating were prepared through in-situ emulsion polymerization and direct mixing methods at varying concentrations of 1, 2, and 3 wt% of nanosilica. Fourier transform infrared (FTIR) spectroscopy revealed that the inclusion of surfactant-containing micelles and a more extended synthesis period in the in-situ synthesis technique enhanced the interaction between silica nanoparticles and polymer chains. Dynamic light scattering (DLS) analysis showed a unimodal distribution and an acceptable range of polydispersity index (PDI) for neat and nanocomposite latexes. The addition of silica nanoparticles enhanced the stability of latex particles, especially evident in the direct mixing method. The field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images confirmed the better dispersion of nanoparticles within the polymer matrix in the in-situ method. The addition of nanosilica resulted in a significant increase in pseudoplastic behavior and viscosity, notably in the in-situ synthesis. In both the in-situ synthesis and direct mixing techniques, the addition of 1 wt% of nanosilica resulted in an increase in the damping factor of nanocomposite films to about 2. However, when the nanosilica content was further increased to 3 wt%, the damping factor decreased. Acoustic tests demonstrated improved sound absorption with silica nanoparticles, yielding noise reduction coefficient (NRC) values of 0.49 and 0.46 for in-situ synthesis and direct mixing. The direct mixing method notably enhanced tensile properties at all nanoparticle content levels. Dried nanocomposite films exhibited superior UV-blocking capabilities compared to neat polymer films.

Incorporation of Silica Nanoparticles in Dental Stone Type IV: Effects on Setting Time

Introduction: This study aimed to examine the setting time of dental stone type IV by adding different percentages (0.5, 1, 2, 5) of silica nanoparticles. Materials and Methods: In this in vitro study, silica nanoparticles (silicon dioxide) were added to dental stone type IV at concentrations of 0.5%, 1%, 2%, and 5% by weight. Forty samples were divided into five groups: 0.5%, 1%, 2%, 5%, and a control group. The samples were prepared according to the manufacturer's instructions and tested according to the ISO 6873 standard using a Vicat device. The time from the start of mixing until the needle could no longer fully penetrate the mass was measured using a chronometer, and the setting time was recorded. Quantitative data were described using mean and standard deviation, and a one-way ANOVA test was performed using SPSS 26 to compare the results. A significance level of P < 0.05 was set. Results: The addition of silica nanoparticles to dental stone type IV significantly increased the setting time, with the increase being proportional to the concentration of the nanoparticles. The setting time of the group containing 5% nanoparticles was significantly higher than that of the control and the 0.5% group (P value < 0.05). Conclusion: The incorporation of silica nanoparticles into dental stone type IV resulted in a significant increase in setting time, particularly at a concentration of 5%. This increase is within the ISO range and offers advantages in the use of nanoparticles in dental materials.

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.

Largely toughened poly(lactic acid) fabricated by melt blending with thermoplastic polyurethane through interfacial compatibilization induced by simultaneous addition of hydrophobic silica nanoparticles and in situ cross‐linking reaction

Largely toughened poly(lactic acid) fabricated by melt blending with thermoplastic polyurethane through interfacial compatibilization induced by simultaneous addition of hydrophobic silica nanoparticles and in situ cross‐linking reaction

Evaluation of Mechanical Properties of Self-cured, Heat-cured, and Photosensitive 3D Printing Resins After the Addition of Silica Nanoparticles

This study evaluated investigate the addition of silica nanoparticles in autopolymerizable resin and into liquid resin for 3D printing and compare them with CAD-CAM blocks and thermopolymerizable resin, regarding flexural strength and surface roughness. Eight groups (n=12) were created according to the types of materials: autopolymerizable resin (G1-G4), photosensitive resin for 3D printing (G5-G6), PMMA block (G7) and thermopolymerizable resin (G8). Functionalized silica nanoparticles (0.5-1.5 wt%) were added in groups G2-G4 and G6. Mechanical flexural strength, surface roughness and morphological analysis were carried out to evaluate the properties of the samples. One-way ANOVA, followed by Tukey's post-hoc test, was used to evaluate the data. The average surface roughness was higher in group G7 and lower in the G8 group, with a statistical difference (p &lt; 0.001). The G8 and G1-G4 showed no significant difference in surface roughness. The G5 and G6 presented surface roughness higher than that recommended by Borchers and Bollen (Ra=0.2 µm). The incorporation of nanoparticles into self-polymerizing acrylic resins negatively affected the mechanical properties of the material, reducing flexural strength. The G5 and G6 demonstrated the lowest flexural strength (p&lt;0.001), presenting values lower than those recommended by ISO (σ &gt;60 MPa) regardless of the incorporation or not of silica nanoparticles. The G7 presented the highest flexural strength value followed by the G8. Within the limits of this study, it may be concluded that the addition of silica nanoparticles did not improve the flexural strength the G6 and also affected negatively the mechanical properties of self-polymerizing acrylic resins.

Effect of Silica and Alumina Nanoparticles Addition on the Dielectric and Rheological Properties of Shea Oil Methyl Ester

Study’s Excerpt/Novelty This study introduces a novel green nanofluid by incorporating shea methyl ester (SME) with surface-modified Al2O3 and SiO2 nanoparticles, addressing the environmental concerns associated with mineral-based transformer oils. The research highlights that SiO2 nanoparticles significantly enhance the dielectric properties of the base oil while minimally impacting its viscosity, suggesting improved insulation performance. This innovative approach offers a sustainable alternative with superior electrical characteristics, potentially transforming the application of transformer oils in the industry. Full Abstract The increasing environmental and utility concerns of mineral-based transformer oils have impelled research into alternative insulation liquids. This study developed a green nanofluid using a two-step approach, incorporating shea methyl ester (SME) derived from shea butter oil and surface-modified Al2O3 and SiO2 nanoparticles. The dynamic viscosity at 25 °C and dielectric properties of the developed nanofluid were investigated in the frequency range of 0.1–15 kHz. Adding nanoparticles into the SME noticeably increased the oil's viscosity, with SiO2 nanoparticles having the least effect on the base liquid's viscosity. The addition of 0.6 wt% of Al2O3 nanoparticles increased the dielectric loss of the SME at all frequencies (0.1–15 kHz), while the addition of 0.6 wt% SiO2 filler nanoparticles reduced the loss of the base oil at frequencies beyond 4 kHz indicative of an improved electrical property. Adding Al2O3 and SiO2 to the base SME oil obtained higher relative permittivity values. This study successfully developed an SME and single nanoparticle-based nanofluid, incorporating a 0.6 wt% weight fraction of surface-modified Al2O3 and SiO2 nanoparticles. The addition of these nanoparticles increased the dynamic viscosity of the base methyl ester oil, with approximately 43% and 36% increases, respectively. The nanofluid developed by incorporating SiO2 nanoparticles showed promising dielectric performance for its application as an insulation liquid.

Effect of dual dispersion of carbon fiber and silica nanoparticles on recovery performance of shape memory epoxy

Shape memory polymers are utilized in diverse fields, including deployable structures and components, owing to their advantageous properties like low density, cost-effectiveness, and ease of processing. The current study investigates the effect of dual dispersion of carbon fibers (CF) and silica nanoparticles (SN) on the recovery performance of shape memory epoxy composites. CF (0.25 wt.%) reinforced epoxy composite, SN (0.25 wt.%) reinforced epoxy composite, and dual (CF and SN 0.25 wt.% each) dispersed epoxy composite were developed using magnetic stirring and ultrasonic mixing to study the mechanical properties and shape memory behaviour. Flexural strength, tensile strength and fracture toughness of pristine epoxy was found to be 134.38, 52.15 MPa and 1.91 MPa∙m1/2, respectively. The addition of CF resulted in a flexural strength of 135.70 MPa and a tensile strength of 53.01 MPa, while the incorporation of SN led to a flexural and tensile strength of 138.40 and 53.69 MPa, respectively. The fracture toughness of composites after adding CF and SN was found to be 2.22 and 2.39 MPa∙m1/2, respectively. With dual dispersion, the flexural strength of 139.82 MPa, tensile strength of 54.64 MPa, and fracture toughness of 2.75 MPa∙m1/2 were achieved. Dual dispersion has shown improved mechanical properties compared to single dispersion. The introduction of CF slightly decreased the shape fixity ratio (Rf ) and shape recovery ratio (Rr ) of the pristine epoxy from 98.67% and 96.62% to 96.67% and 95.15%, respectively. Similarly, the addition of SN further reduced these ratios to 98.00% and 91.83%, respectively. With a dual dispersion approach Rf and Rr were observed to be about 97.33% and 93.83%, respectively. The addition of fillers led to a reduction in Rf and Rr due to inhibition of polymeric chains, resulting in partial shape recovery. However, recovery time improved from 28 to 23 and 26 s with addition of CF and SN, respectively, in epoxy. With dual dispersion, a speedy recovery was achieved with a recovery time of 21 s. The findings of this study demonstrate the potential of dual dispersed fillers to improve the mechanical and shape memory properties of epoxy, which could find applications in the smart materials and structural engineering.

Thermo-rheological improvement of magnetorheological foam with the addition of silica nanoparticles

Magnetorheological (MR) foam has become a potential soft robotic gripper-based material that can provide a better grasping force and handling objects due to its ability in varying stiffness in correspond to applied magnetic fields. However, MR foams are facing degradation issue that may reduce the storage modulus when often exposed to thermal exposure from the operating system of a device. Therefore, this study focuses on improving the storage modulus and simultaneously enhancing the thermal properties of MR foam. Hence, silica nanoparticles were introduced as an additive to achieve the improvement target. MR foams were embedded with different concentrations of silica nanoparticles from 0 to 5 wt.%, and the corresponding rheological properties was examined under different temperature conditions from 25 °C to 65 °C. The results revealed that increasing temperatures have reduced the storage modulus of MR foams, however, the embedded silica has countered the drawbacks by strengthening the interfacial interactions between CIP-polyurethane foam matrix. In addition, the morphological characteristics of MR foams also showed less debris or peel-off PU foam with silica nanoparticles. Besides, the silica nanoparticles have delayed the thermal degradation of MR foam for approximately 30 °C.

A loose polyethersulfone hybrid nanofiltration membrane incorporated with polyethyleneimine-decorated silica nanoparticles for highly-efficient dye/salt separation

Loose nanofiltration (LNF) is a newly-developing technology for desalting dye-containing saline effluents, but suffers from membrane materials with low permeance and poor dye/salt separation selectivity. Herein, a hybrid polyethersulfone (PES) LNF membrane for dye/salt separation was prepared via a nonsolvent-induced phase inversion method, which was carried out using polyethyleneimine (PEI)-modified silica nanoparticles as a dopant. This design not only featured a hybrid PES LNF membrane with high porosity and small mean pore size, but also partially neutralized its charge and enhanced its hydrophilicity. Hybrid PES LNF membrane from a 21-wt% PES solution with 3-wt% PEI-decorated silica nanoparticles addition was demonstrated to achieve high water permeance (92.0 L m−2 h−1 bar−1) and dyes retention ratio (98.4 % for Congo Red, 98.8 % for Nile Blue A, and 95.1 % for Methyl Blue) accompanied with fully-pass for various salts (Na2SO4, NaCl, MgCl2 and CaCl2). In addition, the hybrid membrane exerted excellent resistances to strong acidic, oxidative and hot water (90 °C) environments and exhibited a pH-sensitive permeability. Multicycle test revealed that the hybrid membrane had high permeance recovery ratio (>92.8 %) and maintained its high dye retention and complete salt permeation even after 10 cycles, manifesting its outstanding fouling resistance and recyclability. Besides, the hybrid membrane repelled 92.6 % of dyes from a simulated wastewater consisting of multiple industry-applied direct dyes and salts after 12 h consecutive test, but allow 100 % of mixed salts passing through the membrane, proving its practical applicability to industrial dyeing wastewater. This study provided a simple and economically feasible route to high-performance LNF membrane production for dye/salt separation, thus popularizing LNF process in dyeing wastewater treatment, organic products purification, and resource recovery.

Engineered Nanocomposite Coatings: From Water-Soluble Polymer to Advanced Hydrophobic Performances.

In this work, a water-soluble (hydrophilic) polymer was used to form a hydrophobic coating on silicon substrates (Si) in a two-step process comprising (i) the transformation of the polymer into an insoluble material and (ii) the structuring of this coating at nanometric and micrometric scales to achieve the desired hydrophobic behavior. Polyvinylpyrrolidone (PVP), a water-soluble commodity polymer, was crosslinked using benzophenone and UV irradiation to produce a water-insoluble PVP coating. The nanometric scale roughness of the coating was achieved by the addition of silica nanoparticles (NPs) in the coating. The micrometric scale roughness was achieved by forming vertical pillars of PVP/NP coating. To prepare these pillars, a perforated polystyrene (PS) template was filled with a PVP/NP suspension. Micrometer scale vertical pillars of PVP/silica NPs were produced by this method, which allowed us to tune the wettability of the surface, by combining the micrometric scale roughness of the pillars to the nanometric scale roughness provided by the nanoparticles at the surface. By adjusting the various experimental parameters, a hydrophobic PVP coating was prepared with a water contact angle of 110°, resulting in an improvement of more than 80% compared to the bare flat film with an equal amount of nanoparticles. This study paves the way for the development of a more simplified experimental approach, relying on a blend of polymers containing PVP and NPs, to form the micro/nano-structured PVP pillars directly after the deposition step and the selective etching of the sacrificial major phase.

Investigating silicon nanoparticles modified sandwich polymer composites for enhanced mechanical performance

ABSTRACT This study investigates the morphology and mechanical behaviour of a bidirectional interply hybrid sandwich polymer composite panel with the addition of silica nanoparticles (SiNPs). The investigation assesses the enhanced performance of sandwich polymer composite panels, focusing on their ability to withstand compression, Euler’s buckling axial load-bearing capacity, and surface roughness when subjected to low-velocity impact events that are barely perceptible for aircraft, automobile, and wind turbines. The composite panel was constructed using interply bidirectional Kevlar, carbon, and glass fibers, an epoxy matrix, and polyurethane (PUR) foam, with the incorporation of four different weight percentages of silica nanoparticles (0%, 2%, and 4% of SiNPs). The sandwich composite panel was fabricated using the hand lay-up technique, following a novel quasi-static stacking sequence method (01 K/01 C/01 G/PUR/01 G/01 C/01 K). Among these composite panels, the addition of 4 wt.% silicon nanoparticles exhibited the highest strength and axial load-carrying capacity compared to the other sandwich composite panels (0 wt.% and 2 wt.%). The mechanical characterisation results showed maximum compressive strengths of ca. 3 MPa, ca. 5 MPa, ca. 10 MPa, and ca. 8 MPa for the 0 wt.%, 2 wt.%, 4 wt.% and 6 wt.% of silica nanoparticles-added composite panels, respectively.

The Effect of Silica Nanoparticles Addition on Removal of Glyphosate Residue from Aqueous Solutions

Al-Tharwani, W.S., M.T. Mohammadali and I.M. Abd al-Ridha. 2024. The Effect of Silica Nanoparticles Addition on Removal of Glyphosate Residue from Aqueous Solutions. Arab Journal of Plant Protection, 42(2): 255-259. https://doi.org/10.22268/AJPP-001231 The aim of this study was to evaluate herbicide Tiller 48% SL (Glyphosate) residues in aqueous water by using silica nanoparticles as adsorption agent to remove glyphosate from aqueous solutions. Results obtained showed that when three concentrations of 10, 15 and 20 ml/L water were used, glyphosate concentration determined immediately after treatment was 3520, 5600 and 7955 mg/L, respectively. The concentration of the herbicide decreased with time and reached 1203 mg/L on the tenth day after treatment. No residues were detected by HPLC 21 days after treatment. The results of the study of the use of Nano-silica as an agent for the removal of glyphosate in aqueous solutions showed that the concentration 200 mg/L nano-silica achieved the highest rate of herbicide removal of 89.37%, outperforming the other two concentrations of 100 and 150 mg/L, which achieved 63.45 and 82.87% removal, respectively. Keywords: Glyphosate, residues, silica nanoparticles, adsorptio

Performance improvement of CSP particle receivers by depositing spinel absorber coatings

The challenging development/modification of particles to meet the requirements of thermal stability, high absorptance and mechanical resistance with minimal economical cost is a key point to attain for the next particle receivers of concentrated solar power plants. The properties of the particles influence the performance of the system, since the concentrated solar radiation is absorbed and stored in these solid materials. In this work, resulting from the studies carried out within the HORIZON 2020 COMPASsCO2 project, the deposition of black-coloured transition-metal oxides with spinel-like structure coatings on different particles is proven. Five different particles (state-of-the-art and innovative) developed by Saint-Gobain have been coated, studied and compared. The coating deposition was adapted to the dip-coating methodology, ensuring high and good reproducibility. The composition of solid particles as well as the composition of the precursor solution, the curing methodology and the number of deposited spinel layers demonstrate that they have a great influence on the solar absorptance value and the abrasion resistance. Therefore, it is essential to find the perfect balance between all these different parameters in order to achieve the best performance of the particles. The addition of silica nanoparticles in the precursor solution provides rougher layers with enhanced absorptance, up to 0.980, on newly developed particles with excellent thermal stability and abrasion resistance.

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.

Enhancement of Cooling Capacity of Refrigerant R-134a through the Addition of CuO and Silica Nanoparticles

Abstract: This study investigates the cooling capacity enhancement of refrigerant R-134a by dispersing copper oxide (CuO) and silica (SiO2) nanoparticles in the base fluid. The nanoparticles were mixed at different concentrations, and their effects on the thermophysical properties and heat transfer characteristics of R-134a were evaluated. Experimental results demonstrated that the addition of CuO and SiO2 nanoparticles significantly improved the cooling capacity of R-134a, highlighting the potential of nanofluids in enhancing refrigeration systems. The demand for efficient and environmentally friendly refrigeration systems has led to extensive research in the field of nanofluids. This study investigates the cooling capacity enhancement of refrigerant R-134a by dispersing copper oxide (CuO) and silica (SiO2) nanoparticles in the base fluid. The nanoparticles were mixed at different concentrations, and their effects on the thermophysical properties and heat transfer characteristics of R-134a were evaluated. Experimental results demonstrated that the addition of CuO and SiO2 nanoparticles significantly improved the cooling capacity of R-134a, highlighting the potential of nanofluids in enhancing refrigeration systems.

Higher stability and better photoluminescence quantum yield of cesium lead iodide perovskites nanoparticles in the presence of CTAB ligand.

Inorganic halide perovskites, such as CsPbI3, have unique optoelectronic properties which made them promising candidates for several applications.Unfortunately, these perovskites undergo rapid chemical decomposition and transformation into yellow δ-phase. Thus, the synthesis of stable cesium lead iodide perovskites remains an actual challenging field and it is imperative to develop a stabilized black phase for photovoltaic applications. For this purpose, a surfactant ligand was used to control the synthesis of inorganic perovskite CsPbI3 nanoparticles. Herein we demonstrate a new avenue for lead halide perovskites with the addition of either hexadecyltrimethylammonium bromide (CTAB) or silica nanoparticles to maintain in the first place; the stability of the α-CsPbI3 phase, and later on to boost their photoluminescence quantum yield (PLQY). The prepared perovskites were characterized using UV-visible absorption spectroscopy, fluorescence spectroscopy, scanning electron microscopy, thermogravimetric analysis and X-Ray diffraction technique. Results show higher stability of α-CsPbI3 phase and improvement in PLQY % to reach 99% enhancement in presence of CTAB. Moreover, the photoluminescence intensity of CsPbI3 nanoparticles was higher and was maintained for a longer duration in the presence of CTAB.

Effects of silica nanoparticles on root characteristics of Zoysia grass and rill detachment capacity in soils treated with hydromulch

It is well known that hydromulching is an appropriate method for controlling runoff and soil erosion. Also, the addition of silica nanoparticles (Nsi) in soil in various ways has been found to be a beneficial technique to improve root characteristics. However, few studies have explored the effects of silica nanoparticles produced from rice husk (as a crop that is exceedingly plentiful in many Asian countries) on soil erosion processes, particularly rill erosion due to overland flow in deforested lands. To fill this gap, this study has evaluated the impacts of root growth induced by silica nanoparticles (Nsi) on the rill detachment capacity (Dc) and erodibility (Kr) in the hydromulched soil samples, compared to the control soil samples in deforested lands of Northern Iran. Dc has been measured by a hydraulic flume under four bed slopes (7.3, 13.9, 18.5, and 23.4%) and five water discharges (0.25, 0.36, 0.47, 0.59, and 0.72 L m−1 s−1) with six replications per experiment. Moreover, after the application of hydromulch on soil surface and the growth of grass, root traits (root diameter, root length, root biomass and root weight density) were measured. The results show that rill detachment capacity was lower (on average −59%) in the hydromulched soil with the presence of silica nanoparticles compared to the untreated plot (P < 0.01). Dc was negatively correlated with the root length, root biomass and root weight density. Conversely, as the root diameter increased, the Dc increased. Rill erodibility, obtained by regressing Dc on shear stress, was noticeably lower (-86%) in the hydromulched soil with the presence of silica nanoparticles compared to the bare plot. Overall, the results of this study confirm that the effects of silica nanoparticles on growth development of root traits and the reduction of soil erosion appear to be impactful, especially on steep slopes.

Microstructure characteristics, stress–strain behaviour, fresh properties, and mechanical performance of recycled plastic aggregate self-compacting concrete modified with nano-silica

Reuse of recycled plastic in the construction industry is a novel approach instead of landfilling. However, the utilization of recycled plastic aggregates (RPA) aggravated the majority of concrete properties. In previous investigations, different techniques such as surface treatment of RPAs were utilized to reduce the negative influence of the RPAs on the concrete performance. Research regarding the improvement of RPA self-compacting concrete (SCC) properties by the addition of nano-silica particles (NS) is scarce. Therefore, the current study aims to experimentally investigate the properties of the SCC-incorporated RPAs modified with NS. The experimental program contained sixteen different mixtures which were subdivided into three stages. In the first stage, the effect of NS addition on the performance of SCC mixtures was evaluated. Moreover, the effect of different percentages of RPAs was investigated in the second phase. In the third stage, the optimum percentage of NS particles found in the first stage was utilized to improve the performance of SCC mixtures which aggravated in the second stage. The total binder content for all mixtures was 500 kg/m3 which contained 70 % of cement, 20 % of ground granulated blast furnace slag (GGBFS) and 10 % silica fume. In the first stage the cement was replaced by 1 %, 2 %, and 3 % NS particles, while, in the second stage, the natural fine aggregate (NFA) was replaced by RPAs at six volume fractions (5 %, 10 %, 15 %, 20 %, 30 %, and 40 %). The fresh behaviour of all SCC mixtures was investigated to assess the flowability, filling ability, passing ability, and cohesiveness of the mixtures. The mechanical behaviour was evaluated for compressive strength, splitting tensile strength, modulus of elasticity, flexural strength, and stress–strain behaviour. Moreover, the microstructure characteristics were investigated to illustrate the modifications that occurred in the microstructure scale. The results indicated that the addition of an optimum percentage of NS particles can significantly restore most properties of RPASCC which were degraded due to the addition of RPAs. This technique can help the construction industry to safely use the RPAs in the SCC mixtures without concern about their negative impact on concrete performance.

Suppression of Membrane Degradation Accompanied with Increased Output Performance in Fuel Cells by Use of Silica-Containing Anode Catalyst Layers.

Polymer electrolyte membranes (PEMs) for fuel cells are chemically degraded by the attack of ·OH radicals generated from the decomposition of H2O2, which is predominantly produced at the Pt/C hydrogen anode. The incorporation of conventional radical scavengers into the PEM suffers from a decrease in the output performance. We, for the first time, demonstrate that the addition of hygroscopic silica nanoparticles (NPs) to the Pt/C anode catalyst layer provides a remarkably prolonged (ca. 4 times) lifetime of a Nafion membrane in an accelerated stress test and open circuit voltage (OCV) holding at 90 °C, accompanied by improved output (I-E) performances at low relative humidity. It has been found that the use of silica NPs decreases H2O2 formation rate from the OCV to a practical H2 oxidation potential in a half-cell using 0.1 M HClO4 at 90 °C and provides reduced ohmic resistance (increase in water content) and effective utilization of Pt cathode catalyst in a single cell, by which the improvement of the durability of the PEM and increased output performance are explained rationally.