Synthesis and characterization of aryl substituted functionalized graphene sheets and their electrochemical behavior

Journal of Solid State Electrochemistry - We report the electrochemical behavior of free-standing functionalized graphene sheet electrode in a potential window corresponding to that of high-voltage...     

Cooling curve thermal analysis of Al–Mg2Si–Cu–xSr composite

Journal of Thermal Analysis and Calorimetry - In situ composites are today being considered for industrial use, owing to the fewer production steps involved, lower production cost, and better...     

A fast Pareto genetic algorithm approach for solving expensive multiobjective optimization problems

We present a new multiobjective evolutionary algorithm (MOEA), called fast Pareto genetic algorithm (FastPGA), for the simultaneous optimization of multiple objectives where each solution evaluation is computationally- and/or financially-expensive. This is often the case when there are time or resource constraints involved in finding a solution. FastPGA utilizes a new ranking strategy that utilizes more information about Pareto dominance among solutions and niching relations. New genetic operators are employed to enhance the proposed algorithm’s performance in terms of convergence behavior and computational effort as rapid convergence is of utmost concern and highly desired when solving expensive multiobjective optimization problems (MOPs). Computational results for a number of test problems indicate that FastPGA is a promising approach. FastPGA yields similar performance to that of the improved nondominated sorting genetic algorithm (NSGA-II), a widely-accepted benchmark in the MOEA research community. However, FastPGA outperforms NSGA-II when only a small number of solution evaluations are permitted, as would be the case when solving expensive MOPs.     

Differential toxicity of amorphous silica nanoparticles toward phagocytic and epithelial cells

The objective of this study was to evaluate the influence of size and surface functionality of amorphous silica nanoparticles (SNPs) on their interaction with cultured cells. The intracellular uptake, phagocytic activity, and possible mechanisms of toxicity induced by SNPs were studied on murine alveolar macrophages and two epithelial cancer cell lines. It was found that phagocytic cells are more susceptible to amorphous SNPs than epithelial cells. SNPs with functionalized surfaces were capable to induce the formation of apoptotic cells to a higher extent than plain particles. Plain SNPs induced plasma membrane damage in phagocytic cells to a higher extent and caused cell death in a shorter period of time than surface-functionalized SNPs. The prevalence of necrotic mode of cell death was observed after treatment with plain SNPs. In the range studied surface functionality played an important role in SNPs toxicity.     

Polymerization of a Photocleavable Monomer Using Visible Light

The polymerization of the photocleavable monomer, o‐nitrobenzyl methacrylate (NBMA), is investigated using photoinduced electron/energy transfer reversible addition‐fragmentation chain transfer polymerization. The polymerizations under visible red (λ _max = 635 nm, 0.7 mW cm⁻²) and yellow (λ _max = 560 nm, 9.7 mW cm⁻²) light are performed and demonstrate rational evidence of a controlled/living radical polymerization process. Well‐defined poly(o‐nitrobenzyl methacrylate) (PNBMA) homopolymers with good control over the molecular weight and polymer dispersity are successfully synthesized by varying the irradiation time and/or targeted degree of polymerization. Chain extension of a poly(oligo(ethylene glycol) methyl ether methacrylate) macro‐chain transfer agent with NBMA is carried out to fabricate photocleavable amphiphilic block copolymers (BCP). Finally, these self‐assembled BCP rapidly dissemble under UV light suggesting the photoresponsive character of NBMA is not altered during the polymerization under yellow or red light. Such photoresponsive polymers can be potentially used for the remote‐controlled delivery of therapeutic compounds.

     

Preparation and Characterization of Functionalized Polyaniline-Based Nanocomposite as an Antibacterial Agent

Polyaniline-co-phenylenediamine (PAn/PDA) nanocomposite has been prepared in the aqueous medium using sodium dodecyl benzene sulfonate (DBSNa) and hydroxypropylcellulose (HPC) as a surfactant. The tests used in this research to characterize the products were SEM, TEM, FTIR, UV–Visible and TGA for morphology, particle size, chemical structure and stability. The results confirm that the spherical nanocomposites (40–90 nm) were formed with high thermal stability. It is shown in the results that the physicochemical properties of poly(alkyl substituted anilines) are depended on the substituent groups that are bonded to N-position. The prepared nanocomposites were then tested for the antibacterial properties against three pathogenic strains. The antibacterial properties of nanocomposites were investigated by disk diffusion, minimum inhibitory concentration (MIC), minimum bactericidal concentrations (MBC), and bactericidal kinetic methods. The disk diffusion result indicated that the diameter of the inhibition zones of PAn/PDA–HPC nanocomposite was 9, 11, and 10 mm against E. coli, P. aeruginosa, and S. aureus respectively. It was found that the value of MIC of PAn/PDA–HPC nanocomposite against E. coli, P. aeruginosa and S. aureus were 2.5, 1.25 and 2.5 mg/mL respectively. The evaluation results revealed the PAn/PDA–HPC nanocomposite exhibited excellent inhibitory activity against both gram-negative and gram-positive bacteria.     

Impact of lipid substitution on assembly and delivery of siRNA by cationic polymers

Characterization of a polymer library engineered to enhance their ability to protect and deliver their nucleotide cargo to the cells is reported. The ζ-potential continuously increased with higher polymer:siRNA weight ratio, and the ζ-potential of lipid-modified polymers:siRNA complexes were higher than PEI2 at all ratios. At polymer:siRNA ratio of 1:1, all lipid-substituted polymers showed complete protection against degradation. Lipid-modified polymers significantly increased the cellular uptake of siRNA complexes and down-regulation of GAPDH and P-gp (max. 66% and 67%, respectively). The results indicate that hydrophobic modification of low molecular PEI could render this otherwise ineffective polymer to a safe effective delivery system for intracellular siRNA delivery and protein silencing.     

Spectrophotometric Simultaneous Determination of Zinc(II), Manganese(II) and Iron(II) in Pharmaceutical Preparations Using OSC-PLS

The purpose of this paper is to develop a fast and sensitive spectrophotometric method for the simultaneous determination of zinc(II), manganese(II) and iron(II) in pharmaceutical preparations. The method presented in this work is based on the well-known reaction of these ions with 4-(pyridylazo)resorcinol (PAR)1. The application of quantitative chemometric methods, particularly PLS to multivariate chemical data is becoming more widespread owing to the availability of digitized spectroscop…     

New existing results for a system of nonlinear third-order differential equation via fixed point index

By using fixed point index theory, we investigate a system of nonlinear third-order differential equation. We give some sufficient conditions for the existence of at least one or two positive solutions to the system of nonlinear third-order differential equation. As applications, we also present two examples to demonstrate the main results.     

Effect of citric acid and starch as emulsifier on phase formation and crystallite size of lanthanum oxide nanoparticles

Lanthanum oxide nanoparticles were synthesized via thermal decomposition method of the lanthanum nitrate in the presence of citric acid or starch as emulsifier. The effects of emulsifier and calcination temperature were investigated on the phase transformation and particle size distribution of the products. La₂O₃ nanoparticles were synthesized by drying lanthanum precursor and emulsifier solution, followed by calcination process at 600 and 900°C, respectively. Products were characterized by Fourier Transform Infrared (FT‐IR) spectroscopy, X‐ray diffraction (XRD), thermal analysis (TG/DTA) and nitrogen adsorption method (porous characteristics). The morphology of the samples analyzed using scanning electron microscopy (SEM). Average crystallite size of the products was calculated by XRD data and average particle size was measured from the TEM micrographs. Lanthanum dioxycarbonate in different forms of the tetragonal and monoclinic is crystallized in the presence of citric acid and starch during the calcination at 600°C, respectively. The hexagonal structure, however, is detected as the only crystalline phase formed by calcination at 900°C.