From appropriation to formal intervention: An analytical framework for understanding the appropriation process in residual spaces of Cairo

The paper addresses the issue of how residual spaces are intervened upon through formal and informal processes. It argues that a profound understanding for the dynamics of informal interventions, denoted by appropriation, could enhance the performance of their formal peers.Adopting a qualitative approach, the paper departs from Lefebvre’s unitary theory of space and arrives at an analytical framework that helps to understand the appropriation processes in residual spaces. It, then, attempts to empirically challenge the applicability of this framework through analyzing a Cairene residual space that has undergone two cycles of intervention: a formal and informal one.     

An onsite demonstration and validation of LiDAR technology for wind energy resource assessment

The investigation of wind resource at higher heights is very crucial in planning wind power project. Normally, this involves the installation of a high and costly meteorological mast with a cup anemometer and wind vanes. This investigation uses the new ground-based remote-sensing technique Light Detection and Ranging (LiDAR) to investigate the wind resource at higher heights. This paper describes the LiDAR technology principle and examines the potential of LiDAR measurement to estimate the wind resource at higher heights by conducting a measurement campaign at Tamil Nadu, India. The wind statistics were determined using the 10?min average time-series wind data monitored by ZephIR LiDAR. These include the Weibull parameters, daily mean wind speed, wind power density, wind energy density, vertical wind speed profile and capacity factor. The investigation reveals that the vertical wind speed profile measured from the LiDAR system has approximate closer values to the standard meteorological measurement.     

Fuzzy-modeling with Particle Swarm Optimization for enhancing the production of biodiesel from Microalga

Biodiesel is one of the promising energy sources that could replace petroleum oil in the near future. Microalgae is occupying a distinguished position among the promising sources for biodiesel production. Enhancement of the lipids production during the pretreatment is a key factor for the biodiesel production. High-pressure homogenizer is a better pretreatment procedure to enhance the lipid extraction from microalgae. In this research, a robust model of biodiesel system using fuzzy logic is built based on the experimental data for biodiesel system. Then, Particle Swarm Optimization (PSO) optimizer is applied for determining the best operating parameters of biodiesel system. The decision variables used in the optimization process are; pressure, number of passes, and reaction time that maximizes the percentage of recovery lipids of biodiesel. A comparison study was carried out between the optimized results thought PSO algorithm and those obtained by the experimental results and the optimized results through the Response Surface Methodology (RMS). Results demonstrated that using the proposed optimization methodology is significantly better than RSM, a nearly 78.7% increase in lipids extraction could be achieved according to the current model.     

Saliency-based framework for facial expression recognition

This article proposes a novel framework for the recognition of six universal facial expressions. The framework is based on three sets of features extracted from a face image: entropy, brightness, and local binary pattern. First, saliency maps are obtained using the state-of-the-art saliency detection algorithm “frequency-tuned salient region detection”. The idea is to use saliency maps to determine appropriate weights or values for the extracted features (i.e., brightness and entropy).We have performed a visual experiment to validate the performance of the saliency detection algorithm against the human visual system. Eye movements of 15 subjects were recorded using an eye-tracker in free-viewing conditions while they watched a collection of 54 videos selected from the Cohn-Kanade facial expression database. The results of the visual experiment demonstrated that the obtained saliency maps are consistent with the data on human fixations. Finally, the performance of the proposed framework is demonstrated via satisfactory classification results achieved with the Cohn-Kanade database, FG-NET FEED database, and Dartmouth database of children’s faces.     

The Tail Effect of Some Prepared Cationic Surfactants on Silver Nanoparticle Preparation and Their Surface,Thermodynamic Parameters,and Antimicrobial Activity

The surface parameters of some cationic surfactants having different hydrophobic alkyl chains were assessed in aqueous solution using different techniques; surface tension, ultraviolet-Visible (UV–Vis) spectroscopy, and conductivity measurements. The obtained critical micelle concentration (CMC) for N-(2-((3,4-dimethoxybenzylidene)amino)ethyl)-N,N-dimethyloctan-1-aminium bromide (DBAO), N-(2-((3,4-dimethoxybenzylidene)amino)ethyl)-N,N-dimethyldodectan-1-aminium bromide (DBAD), and N-(2-((3,4-dimethoxybenzylidene)amino)ethyl)-N,N-dimethylhexadectan-1-aminium bromide (DBAH) in aqueous solution using three techniques are nearly the same. Increasing the hydrophobic chain length enhances micelle formation. Raising the solution temperature from 25 to 65 °C also shows the same trend. The thermodynamic calculations outlined the adsorption propensity of the surfactants at the surface compared to their affinity to form micelles. Both micellization and adsorption processes are enhanced with both the hydrocarbon elongation and with raising the solution temperature. The effect of the surfactant tail on the preparation process of the silver nanoparticles (AgNP) was assessed and confirmed using transmission electron microscope (TEM), dynamic light scattering (DLS), and UV–Vis spectra. Increasing the surfactant tail leads to a smaller particle size with a narrow distribution. The stability of the prepared AgNP is enhanced with hydrophobic surfactant tail elongation as proved with increasing the zeta-potential of the prepared AgNP colloid. The foaming power, interfacial tension, and emulsification stability of the DBAO, DBAD, and DBAH surfactants were determined. The DBAO, DBAD, and DBAH surfactants showed good antimicrobial activities against both bacteria (Gram positive and negative) and fungi, which have been enhanced because of incorporation of AgNP.     

Synthesis,complexation and biological effects studies of new thiacrown ethers derived quinoline: part I

A series of new thiacrown ethers derived quinoline 7–9 were synthesized in good yield and in a simple way. Their transition metal ions complexation was studied using a conductometric method in acetonitrile at 25°C. Crowns 7 and 8 showed a continuous decrease in the molar conductances in their complexation with Ag⁺, Cu²⁺, Hg²⁺ and Zn²⁺ which begins to level off at a molar ratio of 1:1 crown to metal, indicating the formation of 1 stable 1:1 complex. On the other hand, crown 9 showed the formation of 1:1 complexes only with Ag⁺, Cu²⁺, Hg²⁺. The in vitro, a preliminary antimicrobial, antioxidant and cytotoxic effects on breast tumor cells were also reported. Five bacterial test strains were included in the present study. Antioxidant activity was measured in terms of the radical scavenging ability and decolorization of 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radicals. Cytotoxic effect of thiacrown was evaluated using MDA MB-231 cell line (human breast adenocarcinoma, ATCC HTB-26).     

Effect of the nanoparticles in the stability of hydrolyzed polyacrylamide/resorcinol/formaldehyde gel systems for water shut-off/conformance control applications

The main objective of this work is to evaluate the inclusion of nanoparticles to partially hydrolyzed polyacrylamide/resorcinol/formaldehyde gel systems to improve the stability under static and dynamic conditions. Oxide nanoparticles (<100 mg·L⁻¹) of SiO₂, Al₂O₃, MgO, and Cr₂O₃ were employed and characterized by their physicochemical properties. Gels were prepared and subsequently placed at 70 °C for evaluating the nanoparticles influence in gel strength through rheological properties and syneresis measurements. Al₂O₃ nanoparticles showed the highest potential for the reduction of the syneresis phenomena, followed by MgO and Cr₂O₃. The SiO₂ nanoparticles lead to a higher degradation of the gel. As the zeta potential increases, the syneresis of the gel system decreases. The nanoparticles did not significantly affect the storage modulus, describing similar gel strength than the original gel. Also, displacement tests showed an incremental of 64% of oil recovery regarding the system in the absence of Al₂O₃ nanoparticles. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47568.     

Glass microparticle- versus microsphere-filled experimental dental adhesives

This study aimed to formulate antibacterial dental adhesives. Phosphate-substituted methacrylate adhesives were modified with 0–20 wt % copper-doped glass microparticles. Two shapes of microparticles were used: regular shaped (microspheres) and irregular shaped (microparticles). The morphology/composition, roughness, monomer conversion (DC%), thermogravimetric analysis, and antibacterial action against S. mutans and P. aeruginosa and ion release were investigated. The results showed that microspheres produced adhesives with a relatively smoother surface than microparticles did. The DC% of adhesives increased with increasing glass filler content. Filled adhesives showed polymer decomposition at ~315 °C and glass melting at 600–1000 °C. The weight loss percent of adhesives decreased with increasing weight percent of fillers. Glass microparticles at 0–20 wt % significantly increased the antibacterial action of adhesives against both bacteria. Glass microspheres at 0–5 wt % significantly increased the antibacterial action of adhesives against both bacteria. Only 20 wt % microparticle-filled adhesive showed an inhibition zone similar to tobramycin (positive control). Microparticle-filled adhesives (with >5 wt % filler) significantly reduced S. mutans more than their microsphere counterparts. Microsphere-filled adhesives (with ≤5 wt % filler) significantly reduced P. aeruginosa more than their microparticle counterparts. Microsphere-filled adhesives showed higher Cu release than their microparticle counterparts. Accordingly, phosphate-substituted methacrylate filled with glass could be used as an antibacterial adhesive. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47832.     

Nonisothermal crystallization kinetics and stability of leucite and kalsilite from K2O-Al2O3-SiO2 glasses

The crystallization mechanisms and elemental stability of leucite and kalsilite formed from K₂O-Al₂O₃-SiO₂ glasses were investigated by X-ray powder diffraction (XRD), X-ray fluorescence (XRF), Raman spectroscopy and differential scanning calorimetry (DSC). Glass samples with compositions along the leucite-kalsilite tie-line were produced by melt processing and were then heat-treated at 850, 950, and 1250°C for times ranging from 5 minutes to 1000 hours. Kalsilite is an unstable phase that behaves as an intermediate precursor to leucite. Crystalline materials in which kalsilite is the major phase lose potassium upon prolonged heat treatment (1000 hours at 1250°C), in contrast to those with leucite, in which little or no compositional alteration is detected. The formation of leucite from stoichiometric kalsilite is accompanied by the formation of potassium-doped alumina. The activation energies for leucite and kalsilite crystallization, determined via application of the Kissinger equation to thermal analysis data, were 579 and 548 kJ/mol, respectively. Finally, production of pure leucite can be achieved with more favorable crystallization kinetics when starting with off-stoichiometric compositions.