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Experimental work is carried out to study the performance of nanoparticle enhanced phase change materials (NEPCMs) when applied to the Egyptian weather for indoor thermal comfort. Nanoparticle alumina and copper-oxide are used as the additive material into the PCMs 7, 11, 24, 26 and 29. The enhanced PCMs are characterized and tested for thermal performance during solidification and melting cycles. Observations are then made to conclude that, compared to the base fluid, PCM11 has the optimum performance for the Egyptian winter weather and PCM26 is the best for the summer conditions. PCM11 with a favorable phase change range ∼11–13∘C for Egyptian winter conditions, shows a reduction of melting time by over 10% when 5wt.% CuO nanoparticles (NPs) are added. Similarly, further to thermal stability and reduced corrosive action, PCM26 enhanced with 5wt.% CuO NPs has over 14% faster melting compared to the base fluid and does not undergo supercooling when tested for summer application. [ABSTRACT FROM AUTHOR]

Concrete technologists use different types of additives such as fly ash, slag, natural pozzolans and nanomaterials toenhance concrete performance and durability. However, a detailed explanation of the early-age hydration process and microstructural modification of concrete in the presence of nanomaterials remains to be presented and extensive research is required for strategic modification of cementitious systems. This study focused on the precise monitoring of early-age hydration with the incorporation of nanoalumina (nAl) in tricalcium silicate (C3S) and Portland cement paste and mortar. The dosage of nAl was varied from 1 to 5% (by weight) in C3S and from 0.1 to 1.0% in Portland cement, with a water/cement ratio of 0.4. The hydration studies showed that the nAl increased the cross-linkage in calcium silicate hydrate gel through substitution of aluminium by silicon, which was responsible for the enhancement of the modulus of elasticity (by 40%) with 1.0% nAl) after 7 days of hydration. In summary, the incorporation of nAl modified the concrete microstructure in the initial days of hydration, leading to higher concrete performance and longer service lives of concrete structures. [ABSTRACT FROM AUTHOR]

As an internal curing substance for cementitious materials, superabsorbent polymer (SAP) is emerging as the most potential solution. Nanomaterials and their composites have wide applications in concrete mainly as crack sealants and viscosity modifiers. Silane, as a coupling agent, is utilized in cementitious materials for its effective particle dispersion and adhesion characteristics. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Thermogravimetry (TGA) analysis, and Scanning electron microscopy (SEM) are utilized to characterize the microstructures and phase compositions of nanoalumina, (3-aminopropyl) triethoxysilane (APTES) and polyacrylamide (PAM) SAP. The impacts of silane-functionalized nanoalumina combined polyacrylamide SAP in cementitious materials are carefully investigated in this work. Compared with plain SAP, the application of silane-functionalized SAP was found to exhibit increased compressive strength, flexural strength and split tensile strength of concrete. The chemical durability properties of cement mortar, rheological and mechanical properties of concrete under self-curing and water curing with cement replaced by the prepared composites at 0.1, 0.2, 0.3, 0.4 and 0.5% by weight of cement are studied experimentally. Results revealed that silane-functionalized nanoalumina modified SAP has good water holding capacity than those with individual SAPs contributing to the advancement of internal curing materials in concrete buildings. The weight loss measurements reveal that lower weight loss is observed for the concrete containing SAP/APTES/nanoalumina in chloride, acidic and sulphate media. This work contributes to the advancement in material technologies for the prevention of building fractures. [ABSTRACT FROM AUTHOR]

Municipal solid waste incineration (MSWI) fly ash containing heavy metals is hazardous solid waste that requires safe disposal. Alkali-activated treatment can effectively improve the environmental safety of MSWI fly ash. Due to the low alumina content of MSWI fly ash, the addition of nanoalumina (NA) solves the defect to enhance the ability of solidification/stabilization (S/S) and maximize the utilization of MSWI fly ash. NA/MSWI fly ash solidified body was prepared by alkali-activated technology in this work. In this study, NA was added (0–3 wt.%) to explore its effects on mechanical properties and heavy metal immobilization efficiency of NA/MSWI fly ash solidified body. Research results revealed that when the addition of NA was 2 wt.%, the compressive strength of solidified bodies can significantly increase by 38.0% and 42.8% at 7 and 28 days, respectively. Meanwhile, the leaching concentration of heavy metals in NA/MSWI fly ash solidified body can noticeably reduce with the immobilization efficiency of above 99.5%. Adding NA promoted the ratio of stable state on Pb and Zn in solidified bodies. A series of microscopic characterization analyses indicated that NA stimulated gels and Friedel's salt formation, and N–A–S–H was also found in the NA/MSWI fly ash solidified body, enhancing S/S heavy metals by physical adsorption, physical encapsulation, and chemical bonding. Therefore, this study paves a potential new way for the application of nanomaterials in S/S MSWI fly ash through alkali-activated technology, and nanoalumina is a more promising candidate. [ABSTRACT FROM AUTHOR]

Sol–gel synthesized ceramic α-Al2O3 nanoparticles were mixed with commercially pure Al powder from 0 to 2.5 wt% in composition to prepare nanocomposites. Mixing of the powders was carried out by using two different techniques viz. normal wet-mixing and ultrasonication. Among these two techniques, ultrasonication was found to be more effective method to achieve uniform distribution of nanoparticles. After uniform mixing, the samples were prepared through powder metallurgy route. Hardness, compression and bending test were conducted to investigate the effect of α-Al2O3 nanoparticles on Al. The microstructure of the nanocomposites revealed that the nanoparticles impede the grain growth of Al particles during the time of sintering, which resulted in the grain refinement. Moreover, the strength of the nanocomposite was improved by the subsequent incorporation of nanoparticles. However, beyond 2wt% of nanoparticles content, the bending strength and hardness were reduced considerably. Maximum improvement in the values of compressive and bending strength was found as 64% and 50%, respectively. [ABSTRACT FROM AUTHOR]

In this work, epoxy resin-based composites reinforced with nanoclays, nanoalumina, carbon nanotubes (CNTs) (0.15, 0.50, and 1.50% vol were submitted to morphological characterization by scanning (SEM) and transmission (TEM) electron microscopies, electrical tests through electrical impedance spectroscopy, and electromagnetic analyses (scattering parameters), in the frequency range of 8.2 to 12.4 GHz. SEM images of the CNT composite revealed nanotube clusters in the matrix. The proximity between the CNTs is corroborated by the increase in the electrical conductivity of the composite due to the formation of a long-range electron transport network, which favored the polarization effect, absorption losses (SEA = 1.33 dB), reflection (SER = 3.38 dB) and reflection loss (RL = -6.61 dB at 10.8 GHz). Composites with nanoclays and nanoalumina showed no significant electrical and electromagnetic results.

This research consists of the fabrication of synthetic gels of hydrated calcium silicate (C-S-H gel) and hydrated calcium aluminate silicates (C-A-S-H gel) in aqueous solution oversaturated in calcium hydroxide. These gels were fabricated using nanomaterials with different specific surface area; two nanosilicas (NS), OX50 and A200 (50 and 200 m2/g respectively) and two nanoaluminas (NA), A65 and A130 (65 and 130 m2/g). Mixtures were carried out maintaining a Ca/Si = 2 ratio and variable Al/Si ratios of 0.1, 0.5 and 1. The effect of aluminium incorporation in the C-S-H gel was studied using the nuclear magnetic resonance technique (29Si MAS-NMR), and the information obtained was further processed using the mathematical deconvolution method. Chemical shift bands were delimited to identify the structures. From the results obtained, modifications of the tetrahedral (Qn) in the dreierketten structure were observed in the different combinations, as well as the modification of the bridging tetrahedral (Q2b) due to the presence of aluminium replacing the silica bridging tetrahedron Q2b(1Al). High Q4 values were detected in the C-S-H gel with NS OX50 and this could be associated to a double chain formation very similar to a perfect tobermorite. The length of the mean chains (MCL) was very variable in each blend, but some trends were observed as the Al/Si = 1 ratio and the Al/Si = 0.1 ratio maintain or increases the MCL respectively. The results are interesting and concrete case mixtures with NS OX50 show original trends that have not yet been reported in the literature. Resumen: Esta investigación consiste en la fabricación de geles sintéticos de silicato de calcio hidratado (gel C-S-H) y de silicatos de aluminato de calcio hidratados (gel C-A-S-H) en solución acuosa sobresaturada en hidróxido de calcio. Estos geles se fabricaron utilizando nanomateriales con diferente superficie específica; dos nanosílicas (NS), OX50 y A200 (50 y 200 m2/g respectivamente) y dos nanoaluminas (NA), A65 y A130 (65 y 130 m2/g). Las mezclas se realizaron manteniendo una relación Ca/Si = 2 y proporciones variables de Al/Si de 0,1, 0,5 y 1. El efecto de la incorporación de aluminio en el gel C-S-H se estudió mediante la técnica de resonancia magnética nuclear (29Si MAS-NMR), y la información obtenida se procesó posteriormente mediante el método de deconvolución matemática. Se delimitaron las bandas de desplazamiento químico para identificar las estructuras. A partir de los resultados obtenidos, se observaron modificaciones del tetraedro (Qn) en la estructura dreierketten en las diferentes combinaciones, así como la modificación del tetraedro puente (Q2b) debido a la presencia de aluminio que sustituye al tetraedro puente de sílice Q2b(1Al). Se detectaron altos valores de Q4 en el gel C-S-H con NS OX50 y esto podría estar asociado a una formación de doble cadena muy similar a la de una tobermorita perfecta. La longitud de las cadenas medias (MCL) fue muy variable en cada mezcla, pero se observaron algunas tendencias como que la relación Al/Si = 1 y la relación Al/Si = 0,1 mantienen o aumentan la MCL, respectivamente. Los resultados son interesantes y las mezclas de casos concretos con NS OX50 muestran tendencias originales que aún no se han reportado en la literatura.

Cement-based materials are regarded as one of the most important building materials due to their simple construction process, low energy consumption, and the wide range of raw materials from which they can be synthesized. This paper presents a state-of-the-art review of published results of promising new research and innovation of cement-based materials using nanotechnology, which lead to improved physical-mechanical properties, durability, and sustainability of these materials. The development of nanoscience has a significant impact on building materials. The application of nanomaterials has shown that the properties of conventional cement-based materials can be significantly improved when nanoparticles are included. The addition of nanoparticles in these materials can act as a filler agent, producing a dense matrix and reducing the growth of micro pores. The incorporation of nanomaterials into cement matrix has become a promising area of research. Nano-sized particles are characterized by a high surface area to volume ratio, and many of them are highly reactive. The incorporation of nanoparticles into the cement matrix significantly improves its properties due to the reactivity of nanoparticles and the filling of matrix nanopores. Understanding the complex structure of cement-based materials at the nanoscale leads to the creation of a new generation of these materials, stronger and more durable, with the desired deformation-stress behavior and, possibly, with a full range of “smart” properties. Aluminum oxide (Al2O3) nanoparticles are among the most important metal oxides with promising applications. The role of nano-Al2O3 in improving the physical and mechanical properties of cement-based materials has been noted by many researchers. This article summarises and discusses current knowledge and the latest research regarding the use of aluminum oxide in cement-based materials. [ABSTRACT FROM AUTHOR]

The goal of this paper is to analyze the aging behavior and the mechanism evolution of nano-Al2O3 (NA)-reinforced styrene-butadiene-styrene (SBS) asphalt under different thermal-oxidative aging conditions. First, NA/SBS-modified asphalt and SBS-modified asphalt with different aging levels were prepared. Second, the viscosity and high temperature rheological performance of the specimens were tested and the property-related aging indexes were calculated and compared. Third, a Fourier transform infrared (FTIR) test of the specimen was conducted and the chemical group-related aging indexes were calculated and analyzed. Fourth, gel permeation chromatography (GPC) was used to analyze the molecular weight of the specimens under different aging levels. Then, an atomic force microscope (AFM) was adopted to analyze the microsurface morphology of different specimens. Finally, correlation analysis between property-related indexes and chemical group indexes was conducted. The results show that NA can enhance the thermal-oxidative aging resistance of SBS asphalt. NA can inhibit the increase in sulfoxide groups and the degradation of the SBS polymer with the increase in aging. NA can slow down the formation of large molecule during the aging process. The degree of change in both the bee structures and micromorphological roughness of NA/SBS asphalt is lower than that of SBS asphalt under different aging levels. [ABSTRACT FROM AUTHOR]

The characteristics and properties of fumed oxides depend strongly on various external actions that is of importance from a practical point of view. Therefore, gelation or high-pressure cryogelation (HPC) of aqueous media pure or with 0.1 M NaCl, and mechanochemical activation (MCA) of dry or wetted powders of individual (silica, alumina, their mechanical blends) and complex (silica/titania, alumina/silica/titania, AST1, AST1/A-300) nanooxides were studied to analyze the influence of the nanooxide composition, particulate morphology, and preparation conditions on changes in the morphological and textural characteristics of treated samples. The temperature-pressure behavior of different phases (silica, alumina, and titania) under HPC can result in destroy of complex core-shell nanoparticles (100-200 nm in size) in contrast to small nonporous nanoparticles, NPNP (5-20 nm). The textural characteristics of nanooxides are sensitive to any external actions due to compaction of such supra-NPNP structures as aggregates of nanoparticles, agglomerates of aggregates, and visible structures in powders. The compaction of supra-NPNP enhances the pore volume but much weakly affects the specific surface area (with one exception of AST1) because small NPNP are relatively stable during any external actions (HPC, MCA). The compacted materials are characterized by enhanced mesoporosity shifted to macroporosity with decreasing specific surface area and increasing sizes of nanoparticles or to mesopores with increasing MCA time or amounts of water in wetted powders. At low hydration of the A-300 powder (h = 0.5 g/g), the value of SBET slightly increases if MCA is provided by stirring or ballmilling. Diminution of the freezing temperature from 208 to 77.4 K during HPC results in enhanced compaction of aggregates and agglomerates but this does not practically affect the primary nanoparticles. The degree of decomposition of core-shell nanoparticles of AST1 does not practically increase with decreasing freezing temperature from 208 to 77.4 K. Decomposition of core-shell AST1 particles is inhibited under HPC by added A-300 (1 : 1) working as a damper. [ABSTRACT FROM AUTHOR]

The aim of this study was to explore the influence of the neurotoxicity of nanoalumina on primarily cultured neurons. Normal control, particle size control, aluminum, micron-alumina, and nanoalumina at 50-nm and 13-nm particle sizes were included as subjects to evaluate the level of apoptosis, necrosis, and autophagy in primarily cultured neurons and further explore the mitophagy induced by nanoalumina. The results demonstrated that nanoalumina could induce neuronal cell apoptosis, necrosis, and autophagy, among which autophagy was the most notable. When the autophagy inhibitor was added to the nanoalumina-treated group, it significantly downregulated the protein expression levels of Beclin-1 and LC3II/LC3. Observation under a transmission electron microscope and a fluorescence microscope revealed mitophagy characteristics induced by nanoalumina. Additionally, the neurotoxicological effects induced by nanoalumina were more significant than those induced by aluminum and in a particle size–dependent manner. [ABSTRACT FROM AUTHOR]

In this present study, the preference selection index method (PSI) was applied to identify the best formulation among ceramic fillers such as glass ionomer cement (GIC), nanosilica and nanoalumina nanofiller in the dental composites. The comparative assessment of the effect of nanofillers (nanoalumina and nanosilica fillers) and glass ionomer cement has been evaluated. Dental composites with 0, 10, and 20 wt% of nanoalumina, nanosilica and glass ionomer cement were fabricated. These composites were analyzed for physico‐mechanical and wear properties. The PSI multi‐criteria decision making technique was used to rank the composites with various filler content. The performance defining attributes for the comparative assessment were set as void content, hardness, compressive strength, flexural strength, diametral tensile strength, and wear properties against load and speed. The PSI of dental composite reinforced with 20 wt% nanosilica (DCSi‐20) was maximum (0.896) followed by dental composite reinforced with 20 wt% glass ionomer (DCGi‐20) (0.889) and hence DCSi‐20 demonstrated as most preferred dental composite material followed by DCGi‐20. DC‐0 showed the least preference dental composite materials on the basis of desirable physical, mechanical, and wear properties. Finally, it can be concluded that despite of more void content and low flexural strength, overall performance of glass ionomer is comparable with nanosilica and more significant with respect to nanoalumina. [ABSTRACT FROM AUTHOR]

Although Nanoalumina is widely used in many biomedical applications, its potential toxic effect on pregnant women and developing embryos/fetuses has not been reported. In this investigation, the maternal and developmental toxicity caused by Nanoalumina during gestation and the potential preventive role of the pumpkin seed oil (PSO) were evaluated. Four groups of pregnant rats were orally administered during days 5–19 of gestation as follows: control group, Nanoalumina group (70 mg/kg b.w), PSO- group (4 ml/kg b.w.), and Nanoalumina plus PSO- group. Nanoalumina induced detrimental impacts in pregnancy outcomes, fetal growth retardation, morphological anomalies, hepatic and neural DNA damage, and histopathological changes in hepatic and neural tissues of both mother and fetus, respectively. Furthermore, the level of MDA is significantly increased and activities of GSH and CAT are significantly reduced in both tissues of nanoalumina‐administered rats. PSO co administration improved pregnancy outcomes, fetal growth parameters, DNA damage, antioxidant defenses the histopathological changes of nanoalumina‐gavaged rats and significantly diminished MDA level. Finally, PSO has a preventive role against the detrimental impacts of nanoalumina in dams and fetuses probably via its potential to prevent reactive oxygen species. [ABSTRACT FROM AUTHOR]

Recently, silicone rubber (SiR) is preferably used in high-voltage cable accessories because it offers a wide range of voltage and temperature applications and excellent electrical and mechanical properties. Furthermore, the SiR exhibits flexibility and inhibits oxidation. In this paper, the electrical tree behavior of SiR nanocomposites containing nanoalumina and halloysite nanoclay was investigated; moreover, the nanofiller concentrations were predetermined at 0 vol%, 1 vol%, 2 vol%, and 3 vol%. The electrical tree growth was observed at room temperature at 8 kVrms after tree inception voltage (TIV). The TIV and electrical tree growth in SiR nanocomposites were monitored using an online digital monitoring system, which consisted of a stereomicroscope and a digital camera. The experimental results indicated that the addition of 1 vol%-2 vol% nanoalumina in SiR composite significantly improved the TIV and electrical tree growth rate. However, the addition of 3 vol% nanoalumina in the SiR composite reduced the TIV and accelerated the electric tree growth rate. In the presence of halloysite nanoclay of approximately 3 vol%, the SiR composite showed improved TIV and electrical tree growth rate.

In the present work, the effects of adding nanoalumina and marble dust on the wear behavior of dental composites were investigated. The hardness of dental composite was determined using Vickers micro-hardness tester. A two-body abrasive wear test was performed on the dental wear simulator under the medium of artificial saliva. The experiments were performed as per the Taguchi orthogonal array and steady state condition by varying parameters such as filler content, normal load, sliding velocity, and number of cycles. The hardness results indicated that the incorporation of 5 wt. % of nanoalumina increased the hardness of the dental composite by 12%, whereas the incorporation of 5 wt. % of marble dust increased the hardness of the dental composite by 7%. Also, for the experiments as per the Taguchi orthogonal array, the mean volumetric wear in the case of nanoalumina-filled dental composite was 9.6% less than that of marble dust-filled dental composite. However, in both the cases, the volumetric wear increased with the increase in normal load, sliding speed, and number of cycles but decreased with the increase in filler content. Analysis of variance (ANOVA) of the results indicated that normal load was less significant compared to filler content, sliding speed, and number of cycles.

The aims of the present study were to develop a dental composite filled with silanized nanoalumina and then to investigate the effect of nanoalumina filler on the two-body and three-body wear behavior under distilled water and food slurry medium, respectively. The dental composites were fabricated by adding silane treated nanoalumina filler particle in the weight percentage of (0–3 wt.%) to the matrix of BisGMA, TEGDMA, CQ and EDMAB. Two-body and three-body wear tests were performed in dental wear simulator machine with varying parameters such as normal load, chewing speed and chamber temperature in such a way as to simulate mastication process. Taguchi’s orthogonal array (L16) design, steady state condition and ANOVA were applied to evaluate the optimum parameter for minimum wear and effect of each parameter on the wear performance of dental composites. The finding of the result indicated that mean volumetric wear rate of dental composite in distilled water (i.e. two-body abrasion) was 33.23% more than that of the same composite in food slurry condition (i.e. three-body abrasion).

Cellulose-based aerogel, due to its rich reserves, environmental friendliness and porous structure, is considered as a new type of adsorbents for treating oil and water pollution. However, the functionalization of cellulose aerogel is still required for the efficient increase of its adsorption performance in wide applications. The combination of nanomaterials could significantly improve the adsorption capability of nanocellulose aerogel. In this work, nanocomposite aerogels comprising of nanocellulose and nanoalumina (NC/Al 2 O 3) are produced via a solvent-free method and the effect of weight ratios between nanocellulose and nanoalumina on the adsorption properties of NC/Al 2 O 3 aerogels has been studied. The results reveal that the NC/Al 2 O 3 aerogel with a low density of 5.1 mg cm−3 could obtain the optimal pore microstructures and the highest oil and organic solvent adsorption capacities with the preparation condition under the nanocellulose/nanoalumina weight ratio of 1:0.25 and 0.4 wt% of nanocellulose in aqueous solution. The presence of nanoalumina facilitates the change of microstructure morphologies, the increase of BET specific surface area and the adsorption capacities of NC aerogel. Compared with pure NC aerogel (74.07 ± 1.67, 69.87 ± 1.01, 81.21 ± 3.20, 52.07 ± 1.70, 48.49 ± 1.01, 75.45 ± 3.58 and 87.03 ± 0.46 g g−1 for thiophene, anhydrous ethanol, ethyl acetate, cyclohexane, sesame oil, acetone and dichloromethane, respectively), the NC/Al 2 O 3 aerogel manifests an outstanding adsorption capacity (108.07 ± 0.37, 89.91 ± 4.83, 93.93 ± 3.81, 71.13 ± 2.48, 64.83 ± 2.25, 85.19 ± 3.87 and 117.65 ± 5.68 g g−1, accordingly). By considering the desirable performance features and the convenient fabrication approach, this nanocellulose nanocomposite aerogel might be a feasible alternative for oily waste water recovery and conservation of environment. [ABSTRACT FROM AUTHOR]

External corrosion by soil’s components is a serious problem in many steel structures such as pipelines and tanks, thus many methods are applied to reduce this risk. Nanotechnology almost gives improving for conventional protection methods. Investigation on nano Al2O3 doped polypyrrole coating has been done on carbon steel structures to protect them in two simulated soil environments include (0.01M NaCl + 0.01M NaHCO3) and (0.01M NaCl + 0.01M Na2SO4). Electropolymerization of pyrrole monomer carried out in oxalic acid with suspended nano alumina using cyclic voltammogram method. Characterization of produced film was done by SEM/EDS and the results indicated the uniformly distribution of coating in the presence of nano alumina confirming the presence of Al2O3 NPs by EDS analysis. Also FTIR spectra showed the occurred incorporation between polypyrole and nanoalumina in deposited film on steel surface. The presence of nano alumina behaves as repaired to healing the defects in polymer film by chemical, mechanical and electrochemical factors and then gives long life time for service; this result was concluded through the improving in protection efficiency of Al2O3 NPs/PPy film compared with conventional red paint which is uses to protect carbon steel structures.

Abstract Al-6061 alloy based nanocomposites were synthesized using sol-gel prepared nanoparticles of α-alumina in their varying weight percentages (0, 0.5, 1.5, and 2.5 wt%) via powder metallurgy route. The synthesized nanocomposites were sintered and heat treated under solutionized and T6 conditions. Afterwards, electrochemical corrosion tests were performed in 3.5% NaCl solution to see the effect of nanoparticle addition on the corrosion behavior of the composites. Heat treatment results indicate that solutionized composites exhibit better corrosion resistance as compared to the composites treated under sintered condition. Heat treatment under T6 condition showed poorest corrosion resistance. Nanocomposite reinforced with 0.5 wt% of nanoparticles showed excellent corrosion resistance than that of 1.5 wt% of nanoalumina incorporated composite. After 2.5 wt% incorporation of nanoparticles, the corrosion rate of the composite becomes very high even more than that of the base alloy. Increase of nanoparticle concentration was found to increase their agglomeration at the grain boundary region that increases porosity in the composite. This ultimately increases the corrosion reaction because of the enhanced chemical reactivity. The microstructural examination of the synthesized nanocomposites were found in good agreement with the corrosion rate determined from electrochemical tests. Highlights • Nanoparticles of α-alumina were synthesized by sol-gel method. • Effect of heat treatment and nanoalumina content were studied on Al-6061 alloy. • Solutionized sample showed better corrosion resistance than sintered & T6 samples. • 0.5 wt% sample showed superior property than base alloy and rest of the composites. • Corrosion becomes worse than the alloy after reinforcing 2.5 wt% of nanoparticles. [ABSTRACT FROM AUTHOR]

Ultrahigh performance concrete (UHPC), which is characterized by dense microstructure and strain hardening behavior, provides exceptional durability and a new level of structural response to modern structures. However, the design of the UHPC matrix often requires the use of high quantities of supplementary cementitious materials, such as silica fume, which can significantly increase the cost and elevate the production expenses associated with silica fume handling. This paper demonstrates that a fiber-reinforced composite with properties similar to conventional UHPC can be realized with very low quantities of silica fume, such as 1% by mass of cementitious materials. The proposed UHPC is based on reference Type I cement or Type V Portland cement with very low C3A (2O3 nanofibers, and high-density polyethylene or polyvinyl alcohol macro fibers. Previous research has demonstrated that nanofibers act as a seeding agent to promote the formation of compact and nanoreinforced calcium silicate hydrate (C-S-H) clusters within the interparticle and nanofiber spaces, providing a nanoreinforcing effect. This approach produces a denser and stronger matrix. This research expands upon this principle by adding synthetic fibers to ultrahigh strength cement-based composites to form a material with properties approaching that of UHPC. It is indicated that the developed material provides improved strain hardening and compressive strength at the level of 160 MPa.

Promoted Мo and W catalysts have been prepared in situ via thermal decomposition of precursors, oil-soluble salts Mo(CO), W(CO), С°CHO, and NiCHO. TiO, AlO, and ZrO(NO) · 6HO have been used as the acidic additives. Also, Mo and W unsupported sulfide catalysts have been prepared in the presence of elemental sulfur as the sulfiding agent. The catalysts have been characterized by transmission electron microscopy and X-ray photoelectron spectroscopy. The activity of the catalysts prepared in situ has been evaluated in the hydrogenation reaction of bicyclic aromatic hydrocarbons by the example of model mixtures of 10% solutions of naphthalenes (unsubstituted naphthalene, 1- and 2-methylnaphthalenes, and 1,5- and 2,3-dimethylnaphthalenes) in n-hexadecane. The effect of the precursor/acidic oxide ratio on the activity of the formed catalyst has been found. Hydrogenation of bicyclic aromatic hydrocarbons has been conducted at a hydrogen pressure of 2 and 5 MPa and a temperature of 380 and 400°C for 2 h. Hydrogenation of the unsubstituted aromatic ring has been preferable due to the absence of steric hindrances. The degree of conversion of n-hexadecane under the reaction conditions has been 1.5-7.5% depending on the reaction temperature. It has been found that the activity of the sulfided catalyst in the conversion of 1- and 2-methylnaphthalenes is inferior to the activity of the unsulfided analogue, while partial replacement of TiO by AlO results in a decrease in the conversion of the substrates as opposed to the unsulfided catalysts, in which the use of nanocrystalline AlO promotes an increase in the conversion. [ABSTRACT FROM AUTHOR]

Polymers are commonly used for improving the physical and rheological properties of asphalt. Several methods have been suggested to increase the compatibility between polymers and asphalt. Adding of nanoparticles to asphalt can improve the performance of polymer modified asphalt. This study is about evaluating the performance of Epoxidised Natural Rubber (ENR) modified asphalt using nanoalumina (Al 2 O 3 ) as Additive. In this study, an ultrasonic device was used to disperse Al 2 O 3 at 2, 4, and 6 wt% into base asphalt (BA) and ENR using a high shear mixer. The effects of Al 2 O 3 addition on the base asphalt and Epoxidised Natural Rubber modified asphalt (ENRMA) were then investigated, including the physical properties, storage stability, rheological properties and microstructure of the binders. High compatibility between Al 2 O 3 and ENR led to a better dispersion of ENR in the asphalt, improving the rheological properties of the binder. Based on dynamic shear rheometry tests, Al 2 O 3 reduces the temperature susceptibility of the asphalt and facilitated polymeric modification by improving the compatibility, increasing the viscosity, stiffness, adhesion and elastic behaviour of the binders. Al 2 O 3 also improved the rutting resistance behaviour at high temperatures. The best results were recorded for polymer-modified asphalt containing 6% Al 2 O 3 compared to the base asphalt without any Al 2 O 3 . [ABSTRACT FROM AUTHOR]

Although considerable progress has been made in recent years in field of polymer welding, challenges still remain in using a friction stir welding method to join polycarbonate (PC) composites. This research provides an investigation on the effect of welding parameters (tool’s travel and rotational speeds) on mechanical properties of PC nanocomposite weld lines. PC nanocomposites were prepared with different percentages of Al2O3 nanofiller using a twin screw extruder and injection moulded as sheets in order to ease the welding. Considering various parameters and their levels, optimization of Taguchi experimental design was carried out, an L16 orthogonal standard array was selected and the effective parameter was calculated using analysis of variance of the results. The results indicated that nanoalumina percentage is the most effective parameter on the tensile strength of weld and tool’s travel speed and rotational speed are next effective parameters, respectively. According to signal-to-noise ratio, maximum weld tensile strength (89.5% of base material) is revealed when nanoalumina percentage, tool’s travel speed and tool’s rotational speed were chosen as 1 wt%, 12 mm/min and 1250 r/min, respectively. [ABSTRACT FROM AUTHOR]

Although studies showed effects of nanoalumina (nano-Al 2 O 3 ) on Escherichia coli , no study completely provides understanding on how bacterial cells respond to damages, especially on how they initiate self-defense. In this study, we showed three types of responses of E. coli to damages caused by nano-Al 2 O 3 . Live, dead, and injured, bacteria showed improved survival rates reaching 104%, 116%, and 104% after exposure to 0.1, 1, and 10 mmol/L of nano-Al 2 O 3 respectively. Survival rates improved from 100% to 114%, corresponding to an exposure time of 0–9 h, and from 100% to 127%, corresponding to 0–1000 μg/L Al 3+ . Improvements were noted in survival rates of E. coli K12 MG1655, HB101, DH5α, and K12 MG1655 △lexA treated by nano-Al 2 O 3 in Luria–Bertani (LB) exposure system or K12 MG1655 in LB, normal saline(NS) and H 2 O exposure system. Bacterial cells transformed from long rods to ellipsoidal or nearly spherical as form of self-preservation mechanism; this phenomenon may be related to changes in membrane potential induced by free Al 3+ released from nano-Al 2 O 3 particles. Molecular mechanism of this response involved inhibited gene expression of sythesis and metabolism of carbohydrates, lipids and proteins. Findings presented in this study may improve understanding of potential danger of nanomaterials and control their spread to environmen. [ABSTRACT FROM AUTHOR]

ABSTRACT Poly(vinylcarbazole) (PVK) and PVK-alumina (Al2O3) nanocomposite coatings were electrochemically coated on 316 L stainless steel (SS) substrates for corrosion protection of 316 L SS in 3.5 weight (wt) % NaCl medium. The formation of PVK and incorporation of nanoalumina particles in PVK-Al2O3 nanocomposite coatings were confirmed from attenuated total reflectance-infrared spectroscopy (ATR-IR). Thermal analysis (TG) results showed enhanced thermal stability for the composites relative to PVK. Incorporation of Al2O3 nanoparticles enhanced the micro hardness of PVK coated 316 L SS. The dispersion of alumina nanoparticles was examined via scanning electron microscope (SEM) and tunneling electron microscopy (TEM) and revealed distinct features. The influence of nanoparticles on the barrier properties of PVK and PVK-Al2O3 nanocomposites was evaluated in aqueous 3.5 wt % NaCl by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies. The results proved that PVK nanocomposite coatings provided better protection for 316 L SS than PVK coatings. The drastic increase in impedance values is due to the high corrosion resistance offered by the PVK nanocomposite coatings that arises due to the interaction between Al2O3 nanoparticles and PVK. The highest corrosion protection shown by the 2 wt % nano Al2O3 incorporated PVK composite coatings proved enhanced corrosion resistance compared to PVK. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44937. [ABSTRACT FROM AUTHOR]

The LZS glass-ceramic (19.58 Li 2 O·11.10ZrO 2 ·69.32SiO 2 ) have a high coefficient thermal expansion (CTE) which can be a limitation in some applications. The addition of alumina in a LZS glass-ceramic matrix is able to reduce the CTE significantly. This happens because of the alumina affinity with respect to lithium silicates to form β-spodumene (LiAlSi 2 O 6 ), a crystalline phase having a CTE nearly zero (0.9 × 10 −6 ° C −1 ). In this work, (1–5 vol%) Al 2 O 3 nanoparticles (13 nm) were added to a LZS (3.5 μm) glass-ceramic matrix to prepare composites with the main goal of evaluation the influence of Al 2 O 3 on their mechanical, thermal and electrical properties. Each composition was wet homogenized and then dried at 110 °C for 48 h for disaggregation. The composites, sintered at 900 °C for 30 min, with relative densities between 92% and 98%, showed zircon and β-spodumene as main crystalline phases. The incorporation of increasing additions of nanosized alumina progressively decreases the final density. This makes the properties to slightly decrease, also. The Young's modulus significantly decreases from 111 to 78 GPa of hardness due to the exponential variation with porosity, but the changes of toughness and hardness are much lower. The electrical conductivity was maintained within ±10-7 S·cm-1, and the dielectric constant ranged from 5 to 6 for all compositions. Thermal conductivity ranged around 4.2 to 3.5 W/mK. [ABSTRACT FROM AUTHOR]

In recent years, nanomaterials have made their way into hundreds of biomedical, life-sciences and technological applications. One such nanomaterial of extreme importance is nanoalumina (AlO nanoparticles). This nanomaterial is an epitome of diversity with applications exhibited in the fields of catalysis, cosmetics, theranostics, energy generation, biosensors, drug-delivery, tumor-regression, etc. However, problems persist in terms of biocompatibility, cost-effectiveness, reproducibility and mass-production of nanoalumina by the presently existent physical, chemical and biological methodologies. Herein, we for the first time are presenting a top-down biofabrication method by which size reduction of commercial bulk alumina/aluminum oxide (5 µm) into nanoalumina (5-25 nm) is carried out by a thermophilic fungus Humicola sp. within 96 h of reaction at just 50 °C. The so-formed nanoalumina is highly stable, water dispersible, fluorescent and natural protein capped; characterization engaged standard techniques. These nanoparticles exhibit anti-bacterial properties against Gram-positive Bacillus subtilis strain and may serve as broad spectrum bactericidal agents. We believe that our novel top-down approach may be extensively used in the facile, inexpensive, eco-friendly and reliable fabrication of abundant quantities of nanomaterials of different chemical compositions, sizes and shapes with better control and predictability over the properties as derived from their substrates. The mechanistic aspect of said protocol is underway. [ABSTRACT FROM AUTHOR]

Seal integrity of functional oil wells and abandoned wellbores used for CO 2 subsequent storage has become of significant interest with the oil and gas leaks worldwide. This is attributed to the fact that wellbores intersecting geographical formations contain potential leakage pathways. One of the critical leakage pathways is the cement-shale interface. In this paper, we examine the efficiency of a new polymer nanocomposite repair material that can be injected for sealing micro annulus in wellbores. The bond strength and microstructure of the interface of Type G oil well cement (reference), microfine cement, Novolac epoxy incorporating Neat, 0.25%, 0.5%, and 1.0% Aluminum Nanoparticles (ANPs) with shale is investigated. Interfacial bond strength testing shows that injected microfine cement repair has considerably low bond strength, while ANPs-epoxy nanocomposites have a bond strength that is an order of magnitude higher than cement. Microscopic investigations of the interface show that micro annulus interfacial cracks with widths up to 40 μm were observed at the cement-shale interface while these cracks were absent at the cement-epoxy-shale interface. Fourier Transform Infrared and Dynamic mechanical analysis measurements showed that ANPs improve interfacial bond by limiting epoxy crosslinking, and therefore allowing epoxy to form robust bonds with cement and shale. [ABSTRACT FROM AUTHOR]

An attempt was made to drift nanoalumina particles into concrete pores through electrokinetic treatment. An external electric current (current density = 3 A/m 2 ) was applied for 3 and 15 days in reinforced concrete blocks toward steel reinforcement and microstructural characterizations (i.e. morphology observation and porosity analysis) were performed on concrete fragments of different depth from exposure surface. The morphology observation evidenced transport of nanoalumina from the exposure surface even reaching the rebar-concrete interface (up to 25–30 mm, in 15 days treatment). The porosity analysis of treated samples revealed that reduction of porosity of rebar interface was more pronounced as compared to the exposure surface and the treatment for 15 days was more beneficial for porosity refinement than treatment for 3 days. Effects of the electrokinetic NA treatment on strength of rebar-concrete interface were evaluated through pull-out test. The results showed that by increasing current density, bond strength of rebar-concrete interface increased. [ABSTRACT FROM AUTHOR]

Novel ultra-high molecular weight polyethylene (UHMWPE)/nanoalumina (F100Ay), UHMWPE/acid-treated nanoalumina (F100Aox%-8-y) and UHMWPE/functionalized nanoalumina (F100Aox%-81PEg-MAHxy) as-prepared nanocomposite fibers were prepared by gel-spinning processes. The rod-like features of the original nanoalumina fillers were significantly etched into broken/shorter nanorods and/or shreds by oxalic acid solutions as their concentrations and/or treating time increased. As evidenced by Fourier transform infrared and transmission electron microscopy analysis, PEg-MAH molecules were successfully grafted onto acid-treated nanoalumina fillers through the reaction of the hydroxyl groups of nanoalumina fillers with the maleic anhydride groups of PEg-MAH molecules during their modification processes. The specific surface areas of each Aox%-81PEg-MAHxy functionalized nanoalumina filler reached a maximum value (≧470 m2/g), as the weight ratios of PEg-MAH to acid-treated nanoalumina approached the optimal value at 8. The achievable draw ratio (Dra) values of F100Ay, F100Aox%-8-y and/or F100Aox%-81PEg-MAHxy as-prepared fibers approach a maximal value as the original, acid-treated and/or functionalized nanoalumina contents reach the optimal values at 0.1, 0.1 and 0.075 phr, respectively, in which, the maximal Dra values obtained for F100Aox%-81PEg-MAHx0.075 as-prepared fiber specimens are significantly higher than those of the F100A0.1 and F100Aox%-8-0.1 drawn fiber specimens prepared at the same draw ratios. Moreover, the maximal Dra values obtained for F100Aox%-81PEg-MAHx0.075 as-prepared fibers reached another maximal value as the functionalized nanoalumina fillers were modified using the optimal weight ratio of PEg-MAH to acid-treated nanoalumina at 8. Further investigation revealed that excellent orientation and tensile properties of the UHMWPE nanocomposite fibers can be obtained by ultradrawing the F100Aox%-81PEg-MAHxy as-prepared fibers with proper amounts of well-dispersed functionalized nanoalumina fillers. [ABSTRACT FROM AUTHOR]

Results of research are aimed at determining the possibility of improving the static and fatigue properties of peel-loaded adhesive-bonded joints of S235JR steel with an alumina nanopowder dispersed in an epoxy adhesive. The static properties were assessed in a T-peel test. The high-cycle fatigue strength tests were carried out on an electromagnetic inductor with the resonance frequency of the joint specimen. High-cycle fatigue was analyzed at the limited number of cycles 2 10 . The tests were conducted on the specimens bonded with an Epidian 57 epoxy adhesive and a PAC hardener, whose properties were modified through the introduction of an alumina nanopowder. Four versions of the filled epoxy adhesive were examined, 0.5, 1.5, 2, and 3 wt.% of the dried nanopowder were dispersed in the epoxy adhesive. Fatigue strength tests revealed a significant improvement of the fatigue lifetime of adhesive-bonded joints due to the addition of fillers. In the best case a more than five-fold increase in the fatigue lifetime was obtained (from 199,500 to 1000,000 cycles). The fatigue strength for the best case increased by about 19%. [ABSTRACT FROM AUTHOR]

In this study, nanoalumina (Al2O3) and nanosilica (SiO2) particles are evaluated as tougheners for a high glass-transition temperature (Tg) epoxy system in correlation with liquid composite molding (LCM) processability. The aim of this paper is to directly compare the effectiveness of nanoalumina and nanosilica of the same nominal particle size as epoxy tougheners on the same neat resin system. The epoxy resin system used in this study was Dow D.E.R. 330 amine cured epoxy with a Tg of 150℃. Both particle types are observed to be Tg neutral and increase fracture toughness of the base epoxy system. Between the two particle types, nanoalumina is found to be more effective than nanosilica in terms of achievable fracture toughness at a given particle loading. As resin viscosity increases with particle addition, the addition of fewer particles with the use of nanoalumina is also beneficial to LCM processing where a lower viscosity is preferable. [ABSTRACT FROM AUTHOR]

The work aimed to evaluate the nanoalumina toxicity on the histological architecture, some haematological and biochemical aspects in male albino rats, during acute and sublethal experiments. Rats, in acute experiments, were injected with a single-acute dose of 3.9 g or 6.4 g or 8.5 g of aluminium oxide (Al2O3) kg−1, whereas those of sublethal were injected with 1.3 g of Al2O3 kg−1 2 days−1. One-way analysis of variance indicated that injected doses and the experimental periods were significantly affected by haemoglobin (Hb) content; haematocrit value (Hct); white blood cell (WBC) count; blood platelet (Plt) count; mean corpuscular volume (MCV); mean corpuscular Hb (MCH) and MCH concentration (MCHC). In acute experiments, Hct, WBC count, MCV and Plt were significantly higher than the corresponding controls, whereas Hb, MCH and MCHC markedly decreased. In comparison with the related controls after 1, 3 and 7 days post-injection, red blood cell count, Hb, Hct, WBC count, Plt and MCV were significantly increased, but begun to decrease after 14 or/and 28 days and were associated with a marked decrease in MCH and MCHC. In serum of rats injected with acute or sublethal dose, the concentrations of total protein (TP) and total lipid (TL) were significantly lesser than the corresponding controls, whereas the levels of urea, uric acid, creatinine and the activities of aspartate aminotransferase and alanine aminotransferase were markedly increased. The injected doses were directly proportional with all the studied biochemical parameter, except the TL and TP that exhibited a negative correlation. Histologically, the highest acute and sublethal doses of nanoalumina caused hepatic irregular disarray, necrosis to the hepatic and Kupffer cells that are associated with congested blood sinusoids. The renal tissues characterized by the appearance of inter-tubular congestion that is accompanied by the dilation of the vascular glomeruli that completely occupied Bowman’s capsule and accompanied with partial disappearance of the renal tubule’s brush border. The brain showed a progressive degeneration of neurons in both the experiments. [ABSTRACT FROM AUTHOR]

The aim of this study was to analyze the effect of adding different weight percentages of nanoalumina particles on mechanical properties of resin-based dental composite materials. The composite specimens were prepared by dispersion of different percentage weight fractions (0 wt%, 1 wt%, 2 wt% and 3 wt%) of silane-modified nanoalumina filler in a monomer system containing 50% bisphenol-A glycidyl methacrylate, 49% tri-ethylene glycol dimethacrylate, 0.2% Camphorquinone and 0.8% Ethyl 4-dimethylaminobenzoate. The filler particle before and after silane treatment was characterized using Fourier-transform infrared spectroscopy and transmission electron microscopy. The presence of C = O bond and Si–O–Si linkage between the monomer and filler was clearly indicated. Mechanical behavior of the light-cured samples was evaluated using compressive strength test, three-point flexural strength test, Vicker Micro hardness tests, dynamic mechanical analysis and simultaneous thermal analysis. The results indicated a more than 16% increase in the compressive strength in the samples containing nanoalumina filler particles. Vickers hardness of composite was increased by approximately 28% with respect to unfilled composite. The flexural modulus of composite mixed with alumina nanoparticles was increased from 1.7 to 5.1 GPa, while the values of composite were slightly decreased from 84.5 to 59.5 MPa. The dynamic mechanical analysis result revealed that the glass transition temperature was found to be increased by 30 ℃ compared to unfilled composite. It was also found that the 1 wt% nanoalumina content recorded the highest value of storage modulus. The weight loss profile and thermal stability from thermogravimetric analysis results revealed that the composite filled with 2 wt% nanoalumina content exhibited maximum thermal stability. [ABSTRACT FROM AUTHOR]

The use of nanoalumina and iron-modified pumice (IMP) as adsorbents for removal of nitrate from aqueous solution was investigated. Adsorption experiments were carried out as a function of the pH, contact time, and concentration of nitrate. Both adsorbents were effective for the nitrate removal in a pH range of 4–6, and optimum removal of nitrate ions occurred in a pH 5.0. The adsorption of nitrate on both adsorbents reached equilibrium within 50 min. Nitrate sorption kinetics was well fitted by pseudo-second-order model. The maximum nitrate uptake capacities for nanoalumina and IMP were found to be 70.8 and 86.7 mg g−1, respectively. The kinetic results showed that the nitrate sorption to nanoalumina and IMP followed pseudo-second-order kinetics with a correlation coefficient greater than 0.99. The equilibrium data for both the adsorbents for nitrate removal were fitted to Langmuir and Freundlich isotherms, but the experimental data were found to be little better fitted by the Langmuir model. These results indicate that nanoalumina and IMP are interesting alternatives for nitrate removal from the aqueous solution. [ABSTRACT FROM PUBLISHER]

The present study shows the experimental results about the physical properties and microstructural changes of Portland cement with y and a alumina nanoparticles. All alumina samples were synthesized from an industrial byproduct. Cement matrix was additivated with nanoalumina at different quantities (from 0.5% up to 1% by weight of cement). Porosimetry and gas permeability tests on the hardened cementitious systems were performed. Results showed a 40% decrease in permeability for y-Al2O3 system. The surface analysis of the y-Al2O3-based cementitious specimens was carried out, resulting in a substantial decreasing of their surface area and pore volume in comparison with the reference material. Additionally, a-Al2O3-based cement systems showed less proportion of amorphous CSH gels and portlandite crystals were predominant. In contrast, y-Al2O3 -based composite materials exhibit well defined etringite crystals (needle-like structures), further remarkable changes in the CSH gel morphology, impacting on the macroscopic mechanical properties. [ABSTRACT FROM AUTHOR]

The influence of incorporation of micro and nano sized particles such as fly ash, silica fume, nanosilica and nanoalumina on the hydrated cementitious system is studied. The transformation in the hydrated products due to these additions are analyzed using X ray diffraction and scanning electron microscopy. Further, transition in the pore structure owing to the formation of hydrated products are evaluated through nitrogen adsorption/desorption (NAD) technique method and image analysis. The pore structure is characterized by the total pore volume and pore size distribution using NAD method and pore area fraction from image analysis. It is found that the micro and nano additions do not always improve the microstructure by reducing the pores, sometimes (in case of addition of nano materials/silica fume) increase the size of the pores by pore widening phenomena. Neverthless, it is realized that the nano alumina addition helps in filling the pores only at later ages. [ABSTRACT FROM AUTHOR]

High-pressure cryogelation (HPC) of individual (silica, alumina, their mechanical blends) and complex (silica/titania, alumina/silica/titania, AST) nanooxides were studied to reveal the influence of nanooxide composition and gelation conditions on changes in the textural characteristics of the materials. The temperature-pressure behavior of different phases (silica, alumina, and titania) under HPC can result in destroy of complex nanoparticles, especially large (100-200 nm in size) core-shell secondary nanoparticles composed of a number of small primary nanoparticles (~10 nm in size) covered by a shell destroyed under HPC. The main changes in the texture of HPC or gelled nanooxides are due to rearrangement (compaction) of secondary structures such as aggregates of primary nanoparticles and agglomerates of aggregates. This compaction enhances the pore volume but much weakly affect the specific surface area (with one exception of AST) because small primary nanoparticles (10-20 nm in size) are relatively stable during HPC. The HPC materials are characterized by enhanced mesoporosity shifted to macroporosity with decreasing specific surface area and increasing size of primary nanoparticles. Diminution of the freezing temperature from 208 to 77.4 K during HPC results in an increase in pressure (up to 1,050 atm in stainless steel freezing bombs) and enhanced compaction of aggregates and agglomerates but this does not practically affect the primary nanoparticles. The degree of decomposition of secondary core-shell nanoparticles of AST does not practically increase with this decreasing freezing temperature. Graphical Abstract: High-pressure cryogelation can destroy core-shell nanoparticles. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Thousands of abandoned wellbores may lie within the aerial extent of a CO 2 storage operation. These wellbores represent a potential leakage pathway and a leaky wellbore needs to be re-completed or otherwise repaired to restore seal integrity and ensure containment of the stored CO 2 . Due to the high cost of recompleting a well, a sufficient economic incentive exists if a viable seal repair technology is available. In this paper, we examine the use of epoxy nanocomposites as potential seal repair materials that have excellent bond characteristics with both steel and cement when cured in the subsurface environment. Test results show Novolac epoxy nanocomposites incorporating nanosilica, nanoclay or nanoalumina to have acceptable flowability that enable injection in wellbore cracks and significantly higher bond strength compared with standard microfine cement. [ABSTRACT FROM AUTHOR]

The current study deals with Cr(VI) removal using a polymer-nano metal oxide based composite film under fluorescent light condition. This was prepared by the layer-by-layer coating of chitosan/polyethylene glycol (PEG) blend, polystyrene sulphate (PSS) and nanotitania/nanoalumina mixture respectively on the glass slide. The Taguchi’s orthogonal array ( L 25 ) design was employed for determining the optimal process factors (pH: 6, reaction time: 10 min and initial Cr(VI) concentration: 20 mg L −1 ) and the film preparation factors (dosage of PEG: 0.5 v/v%, dosage of PSS: 0.25 v/v%, dosage of nanotitania–nanoalumina mixture: 95:5 mg L −1 ). The maximum removal capacity observed at the optimal conditions was 278.9 ± 4.3 mg g −1 . The SEM–EDX, XPS, FTIR–ATR spectra confirmed the photocatalytic reduction of Cr(VI) and binding of Cr(III) species on the PSS layer. A 97% regeneration of the film and a cumulative removal capacity of 2467.6 mg g −1 were observed after nine cycles of reuse. This removal capacity for chromium is about twenty fold higher than that reported by any single nanoparticle so far. [ABSTRACT FROM AUTHOR]

Fumed silica, initial alumina blend, after mechanochemical activation (MCA), and fumed binary silica/alumina (SA) were studied using infrared spectroscopy, X-ray diffraction (XRD), ultrasoft X-ray emission (USXE) spectroscopy (giving emission bands Si L α , Al L α and O K α related to valence electron transfer onto core levels) and quantum chemistry. The MCA influence on nanoparticle characteristics (sizes, electronic structure) increases with increasing alumina content in the blends due to stronger abrasive effect of alumina nanocrystallites (snagging a surface layer of nanoparticles during MCA) than non-crystalline silica nanoparticles. A difference in Si L α , Al L α and O K α affected by MCA increases with increasing alumina content. It is greater for the top peak of the upper valence band (UVB) than for a lower energy peak in the bottom of the UVB. These spectral changes suggest redistribution of electron density between Si, Al and O atoms depending on alumina content, material type and treatment conditions. The main difference in the properties of the SA blends and binary SA is due to distribution of Si atoms in alumina phase and Al atoms in silica phase in fumed SA (which is amorphous at C Al 2 O 3 ≤ 30 wt.%) in contrast to the SA blends with practically separated silica and alumina nanoparticles. [ABSTRACT FROM AUTHOR]

In this paper the authors propose a framework for combining life cycle assessment (LCA) and Risk Assessment (RA) to support the sustainability assessment of emerging technologies. This proposal includes four steps of analysis: technological system definition; data collection; risk evaluation and impacts quantification; results interpretation. This scheme has been applied to a case study of nanofluid alumina production in two different pilot lines, “single-stage” and “two-stage”. The study has been developed in the NanoHex project (enhanced nano-fluid heat exchange). Goals of the study were analyzing the hotspots and highlighting possible trade-off between the results of LCA, which identifies the processes having the best environmental performance, and the results of RA, which identifies the scenarios having the highest risk for workers. Indeed, due to lack of data about exposure limits, exposure–dose relationships and toxicity of alumina nanopowders (NPs) and nanofluids (NF), the workplace exposure has been evaluated by means of qualitative risk assessment, using Stoffenmanager Nano. Though having different aims, LCA and RA have a complementary role in the description of impacts of products/substances/technologies. Their combined use can overcome limits of each of them and allows a wider vision of the problems to better support the decision making process. [ABSTRACT FROM AUTHOR]

Highlights: [•] The core and coating components of engineered nanoparticles were labeled with rare isotopes. [•] These complex nanoparticles were injected into the rat. [•] Dose and tissue samples were analyzed for both rare isotopes. [•] The rare isotope ratio demonstrated that the citrate coating dissociated from the CENP. [Copyright &y& Elsevier]

To study changes in the characteristics of gelled/dried nanooxides (fumed silicas PS300 and PS100, alumina, silica/titania ST, alumina/silica/titania AST), high-pressure cryogelation, HPCG (at 208K or 260K) or gelation (293K, 1atm) was carried out using 20wt.% aqueous suspensions pure or with addition of 0.1M NaCl. The nanooxide samples were studied after drying at room temperature. Maximal changes in the textural and crystalline characteristics are observed for cryogels with AST prepared at ~1000atm and 208K due to decomposition of complex nanoparticles. Its specific surface area SBET increases from 83 to 160m²/g, and the crystallinity degree grows by 11%. Mixing of PS300 and AST (1:1, w/w) in the suspension prevents the decomposition of AST particles in the cryogel since SBET decreases in comparison with that of the initial blend powders. Addition of NaCl (2.8wt.% in dried powders) reduces decomposition of AST particles due to changes in HPCG conditions. For binary ST, SBET increases but much smaller than for AST. HPCG of individual silica and alumina leads to a decrease in the SBET value; i.e. nanoparticles are not decomposed. A significant increase in the volume of large mesopores (pore radius 5-10nm

Crystalline and electronic structures of nanoalumina alone and in different mixtures with nanosilica have been analyzed using X-ray diffraction (XRD) and ultrasoft X-ray emission spectroscopy (USXES). Narrowing of the OKα bands of crystalline alumina occurs with decreasing nanoparticle size. Electron transfer from oxygen to aluminum atoms due to Al-O bond breakage under irradiation leads to occupation of high-energy 3d level of Al. In nanoparticles, the Al-O bond strength and O-O interactions enhanced by Laplace (bubble) pressure lead to δ phase stabilizing if coherent-scattering region size (dCSR) reaches 7 nm which is smaller than that for ϑ phase (dCSR = 11-20 nm) of alumina and silica/alumina studied. The dCSR values are in agreement with nanoparticle sizes calculated using self-consistent regularization method applied to nitrogen adsorption data. [ABSTRACT FROM AUTHOR]