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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]

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]

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]

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]

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]

Vitamin B3 (nicotinic acid, NA) is selected as an example of a promising environmental eco‐friendly metal sequestering reagent to functionalize the surface of nanoalumina‐loaded sodium dodecyl sulfate (nano‐Al2O3‐SDS) sorbent. This reaction is accomplished via microwave‐assisted heating using a solvent‐free approach for the formation of a novel nano‐Al2O3‐SDS‐NA sorbent. The functionalized nanomaterials are characterized by Fourier‐transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. A comparative study is performed to explore and evaluate the sorption behaviors of nano‐Al2O3, nano‐Al2O3‐SDS, and nano‐Al2O3‐SDS‐NA sorbents for removal of Cu(II), Zn(II), and Pb(II) from aqueous solutions by the batch adsorption technique. The desired selectivity characteristics in the evaluated nanosorbents are confirmed from the determined maximum metal sorption capacity values of Cu(ΙΙ), Zn(II), and Pb(II) as 5700, 900, and 700 µmol g−1 by nano‐Al2O3‐SDS‐NA sorbent, respectively, using a 5 mg dosage. The optimum contact pH, time, initial metal ion concentration and competing species are also investigated. The Langmuir, Brunauer‐Emmet‐Teller and Dubinin–Radushkevich adsorption isotherm models are applied to evaluate the interaction processes of Cu(II), Zn(II), and Pb(II) by nano‐Al2O3, nano‐Al2O3‐SDS, and nano‐Al2O3‐SDS‐NA sorbents. The potential applications of these nanosorbents for adsorptive removal of metal cations from real samples are successfully optimized via a micro‐column technique. Nicotinic acid (Vitamin B3) has been employed as a promising eco‐friendly metal sequestering reagent to modify the surface of nanoalumina‐loaded sodium dodecyl sulfate (nano‐Al2O3‐SDS) using a microwave‐heated, solvent‐free approach for the formation of a novel nano‐Al2O3‐SDS‐NA sorbent. The sorption behavior and mechanism of nano‐Al2O3‐SDS‐NA versus nano‐Al2O3 and nano‐Al2O3‐SDS for Cu(II), Zn(II), and Pb(II) from aqueous solutions are explored and evaluated. [ABSTRACT FROM AUTHOR]