Nanoparticles used as an ingredient in different types of concrete

Attempts to modify cement-based mixtures and to improve their properties have always attracted the attention of researchers. Favorable effects of nanoparticles, such as small particle size, high reactivity, and great surface area, have made them be used as one of the best replacements of cement. This paper aims to review the previous researches conducted regarding the effects of nanoparticles on the properties of concretes. Influence of various types of nanoparticles on the workability of fresh composite, mechanical properties such as compressive strength, flexural strength, splitting tensile strength, modulus of elasticity, and abrasion resistance, and durability-related properties such as water absorption, chloride ion penetration, resistance to frost, shrinkage, and carbonation of concrete is discussed.

Valorization of Date Syrup by the Production of Lipopeptide Biosurfactants by a Bacillus mojavensis BI2 strain: Bioprocess Optimization by Response Surface Methodology and Study of Surface Activities

Lipopeptides Biosurfactants are natural surface-active compounds produced by a variety of microorganisms. They have great interest in environmental, biomedical and agro-industrial fields. However, the high cost of culture media and the low yield of production limit their large-scale production and application. The development of efficient and cost-effective bioprocess became of a great interest for the improvement of the yield of biosurfactants and the decrease of production cost. In this aim, we applied the response surface method to optimize an economic biosurfactant production by a newly isolated strain B. mojavensis BI2 on date syrup called “Luegmi” as unique carbon and nitrogen source. Using a Box-Bhenken design, we studied the effect of three independent variables on lipopeptide production; Leugmi concentration, Na 2 HPO 4 and incubation time. The results of this study showed that Leugmi concentration at 25%, Na 2 HPO 4 at 0.1% and incubation time of 24 hours were optimal conditions for biosurfactant production, with a maximum surface tension decreasing capacity of 55% corresponding to 27 mN/m and oil dispersing of 30 cm 2 corresponding to a diameter of 6 cm. Preliminary characterization of the biosurfactant produced on Luegmi by UV-Spectra and Thin Layer Chromatography showed its lipopeptide characters. Physic-chemical characterization of the produced lipopepetide on Leugmi showed its great surface activities and stabilities at different pH, temperature and salts concentration. The results of this study suggested that Leugmi, an agricultural byproducts can be used as a low-cost substrate to enhance the yield of lipopeptide biosurfactants with great surface activities for potential environmental application.

Applications of Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy

The surface-enhanced Raman scattering (SERS) is mainly used as an analysis or detection tool of biological and chemical molecules. Since the last decade, an alternative branch of the SERS effect has been explored, and named shell-isolated nanoparticle Raman spectroscopy (SHINERS) which was discovered in 2010. In SHINERS, plasmonic cores are used for enhancing the Raman signal of molecules, and a very thin shell of silica is generally employed for improving the thermal and chemical stability of plasmonic cores that is of great interest in the specific case of catalytic reactions under difficult conditions. Moreover, thanks to its great surface sensitivity, SHINERS can enable the investigation at liquid–solid interfaces. In last two years (2019–2020), recent insights in this alternative SERS field were reported. Thus, this mini-review is centered on the applications of shell-isolated nanoparticle Raman spectroscopy to the reactions with CO molecules, other surface catalytic reactions, and the detection of molecules and ions.

Throwing light on the current developments of two dimensional metal organic framework nanosheets (2D MONs)

Due to the fascinating features such as ultra-thickness, great surface-to-volume atom ratios, abundantly available unsaturated coordination sites, highly porous structure, enhanced conductivity, and easily tunable structure, considerable research interest in...

Removal of Various Pollutants from Wastewater Using Plasma-modified Lignocellulose-derived as a Low-cost Adsorbent: an Overview.

: In their search for an alternative to commercial adsorbents, much research is turned to the local biomass-based materials such as agricultural residues and assimilated derivatives. However, natural biomass due to its low specific surface area must first undergo several pre-treatments. Among the newly emerging electric techniques for environmental applications, those who operate at atmospheric pressure (Non-thermal plasma) have recently found many breakthrough applications arising from their easy use with no extra additional reagents and their high reactivity. The Non-thermal plasma treatment of biomass is one of the promising developed approaches mainly due to significant effects including the formation of micro and macrospores, the increase of surface roughness, and surface functionalization. The most used plasma is non-thermal, so as not to denature the biomass, likewise the hot plasma can burn and/or destroy high contains carbon biomaterials. Especially, the gliding arc plasma obtained using moisten air as feeding gas, which is known to induce acidifying and oxidizing effects in an aqueous target. The primary species HO• radicals [E° (HO• /H2O) = 2.85 V/SHE] mainly formed in the arc will be with the dimer H2O2 [E°(H2O2/H2O) = 1.76 V/SHE] the determining agents for the chemical reactions induced. Exposure of a target to this kind of environment is likely to promote great surface transformations. This approach has some advantages: (i) the merit of not using commercial chemical reagents, the reactive species being in-situ generated; (ii) the risks related to the manipulation of the products, the plasma reactor is robust and can be modulated to treat large quantity; (iii) the efficiency of the bifunctionality of the plasma (acidifier and oxidative). In this review, we will spotlight the main changes induced by exposure of biomass to plasma treatment and also make a comparative study between chemically and plasma-activated materials in the removal of various pollutants from aqueous solution; and finally we summarize the findings in the existing literature.

“Great Surface Appeal”

Chapter 4 recounts how the United States Department of Justice obstructed missing child legislation in the early eighties but eventually buckled under pressure from activists, who deployed an affective politics of child safety to paint the DOJ as cruel and obstinate. The DOJ subsequently transformed into the federal entity most committed to the child safety cause, working to publicize and combat the problems of child abduction, exploitation, sexual abuse, and pornography. The Department’s “conversion” proved vital to the making of a punitive child safety regime in the late twentieth and early twenty-first centuries.

Preparation of Hexamethyldisilazanomethacryloxyphenyl ketone (HDMK) and its copolymerization in the presence of acrylates

Purpose This paper aims to improve some properties of poly (methyl methacrylate) by copolymerization with butyl acrylate (BA) monomer along with the incorporation of the stable and economical synthesized silicone-containing monomer hexamethyldisilazanomethacryloxyphenyl ketone (HDMK) into the copolymer matrix. Design/methodology/approach For this target solution copolymerization of methyl methacrylate (MMA), BA and HDMK were carried out using a 250 mL four-necked round-bottom flask. Before solution polymerization start-up, the reaction vessel was first charged with 34.8 mL toluene and heated to 170 °C with stirring and reflux cooling. A monomer mixture of 25.86 g (260 mmol) MMA, 26.40 g (200 mmol) BA, 3.00 g (8.60 mmol) HDMK and 0.45 g (2.00 mmol) dibenzoyl peroxide was added continuously from the dropping funnel over a period of 4 h. Findings The HDMK was successfully synthesized and the water resistance of acrylic resins was improved because of the existence of HDMK. Research limitations/implications The materials that were used in this research paper had a reasonably low cost. Also, the procedures for synthesis of monomers and polymers were extremely easy because there was no need for high pressure or temperature and no dangerous solvents were used. Practical implications The acrylic resin that contained HDMK was used to synthesis a white architectural paint for exterior coating. Examining the paint characteristics has shown acceptable washing and abrasion resistance, good brushing, excellent storage stability and great surface coating. Originality/value HDMK was synthesized for the first time.

A New Slip Length Model for Enhanced Water Flow Coupling Molecular Interaction, Pore Dimension, Wall Roughness, and Temperature

In this paper, a slip length model is proposed to analyze the enhanced flow based on the Hagen–Poiseuille equation. The model considers the multimechanisms including wall-water molecular interactions, pore dimensions, fractal roughness, and temperature. The increasing wall-water interactions result in the greater slip length and flow enhancement factor. The increased temperature enhances the kinetic energy of water molecules that leads to great surface diffusion coefficient and small work of adhesion. The wall roughness can decrease the slip length and flow enhancement factor in hydrophilic nanopores. This work studies the effects of multimechanisms on slip length and flow enhancement factor theoretically, which can accurately describe the liquid flow in nanopores.

Polyphenol oxidase/gold nanoparticles/mesoporous carbon-modified electrode as an electrochemical sensing platform for rutin in dark teas

By virtue of great surface area of mesoporous carbon, enhanced conductivity of AuNPs, and good electrochemical response of polyphenol oxidase to rutin, a PPO/AuNPs/FDU-15-modified electrode was used for the determination of rutin in dark teas.

Mesoporous Silica Materials as Drug Delivery: “The Nightmare” of Bacterial Infection

Mesoporous silica materials (MSM) have a great surface area and a high pore volume, meaning that they consequently have a large loading capacity, and have been demonstrated to be unique candidates for the treatment of different pathologies, including bacterial infection. In this text, we review the multiple ways of action in which MSM can be used to fight bacterial infection, including early detection, drug release, targeting bacteria or biofilm, antifouling surfaces, and adjuvant capacity. This review focus mainly on those that act as a drug delivery system, and therefore that have an essential characteristic, which is their great loading capacity. Since MSM have advantages in all stages of combatting bacterial infection; its prevention, detection and finally in its treatment, we can venture to talk about them as the “nightmare of bacteria”.