Adsorption of indigo carmine from aqueous solution using coal fly ash and zeolite from fly ash

Coal fly ash, a waste generated at the Figueira coal-fired electric power plant located in Brazil, was used to synthesize zeolite by hydrothermal treatment with NaOH solution at 100 °C for 24 h. The fly ash (FA) and this synthesized zeolite (ZM) that was characterized predominantly as hydroxy-sodalite were used as adsorbents for anionic dye indigo carmine from aqueous solutions. The samples were analyzed by instrumental neutron activation analysis (INAA) for the determination of As, Co, Fe, La, Mo, Na, Sb, Sc, Sm, Th, U and Zn. Effects of contact time and initial dye concentration were evaluated in the adsorption processes. The kinetics studies indicated that the adsorption followed the pseudo-second order kinetics and that surface adsorption and intraparticle diffusion were involved in the adsorption mechanism for both the adsorbents. The Langmuir isotherm model provided the best correlation of the experimental data. The maximum adsorption capacity was found to be 1.48 mg L⁻¹ for FA and 1.23 mg L⁻¹ for ZM. Laboratory leaching and solubilization tests conducted to classify this ZM as if was a waste residue according to the Brazilian regulation classified it as a residue non-hazardous and non-inert.     

A DFT comparison of the neutral and cationic Heck pathways

The two distinct mechanistic pathways of the Heck reaction, cationic and neutral, are characterized computationally using DFT calculations with corrections for solvation and dispersion. The selectivity in each type of reaction is discussed in terms of the detailed reaction paths, and the two types are compared to each other. The geometries and energies of the selectivity-determining transitions states are analyzed in detail.     

Response surface methodology for optimization of cyanamide analysis by in situ derivatization and dispersive liquid–liquid microextraction

Cyanamide is widely used for agricultural purposes; therefore, its residues can be found in water. A new method was developed for its quantification using in situ derivatization with 2,6‐dimethyl‐4‐quinolinecarboxylic acid N‐hydroxysuccinimide ester followed by dispersive liquid–liquid microextraction (DLLME) and high‐performance liquid chromatography/fluorescence analysis. Multivariate chemometric techniques were successfully used to obtain the optimum conditions for direct derivatization and DLLME extraction. Derivatization parameters and DLLME extraction conditions were optimized by a two‐step design, 2^k factorial design for screening, and central composite design for optimization. Best derivatization conditions were addition of 600 μL of derivatizing reagent, a temperature of 4 ºC, and pH 8.5, whereas for optimum extraction 800 μL of solvent, 30% NaCl conc. w/v, and pH 3.8 were chosen. The analytical performance of the method for routine analysis was evaluated. Excellent linearity was achieved from 10 to 200 µg L⁻¹ with a correlation factor of 0.9996. Precision ranged from 3.5% to 5.5% for intraday assays and 8.5% to 8.6% for interday assays. The mean recoveries performed on water from different origins (ground, river, sea, tap, and mineral) at three levels of concentration (20, 75, and 200 µg L⁻¹) ranged from 90.2% to 110.2%. Copyright © 2014 John Wiley & Sons, Ltd.     

Solid-phase based synthesis of biologically promising triazolyl aminoacyl (peptidyl) penicillins

An efficient and versatile methodology for the preparation of valuable triazolyl aminoacyl (peptidyl) penicillins is described. Solid-phase Cu(I)-catalyzed Hüisgen 1,3-dipolar cycloaddition was used as the key step showing general applicability and excellent regioselectivity either with CuI or [Cu(CH₃CN)₄]PF₆ as Cu(I) source.     

Quadruple domino organocatalysis: an asymmetric aza-michael/michael/michael/aldol reaction sequence leading to tetracyclic indole structures with six stereocenters

Quadruple domino/Wittig-one pot: An organocatalytic, asymmetric, three-component quadruple cascade, which leads to tetracyclic double-annulated indole derivatives, is described. The domino products were further derivatized by aldehyde olefination under one-pot conditions to obtain complex isoindolo[2,?1-a]indole derivatives bearing six stereogenic centers in a highly stereoselective fashion.     

Fourth ANKA and KNMF User Meeting 2012

On October 10–11, 2012, the ANKA synchrotron radiation facility and the Karlsruhe NanoMicro Facility (KNMF), both user research facilities at the Karlsruhe Institute of Technology (KIT) in Germany, hosted their fourth joint annual user meeting at the Ettlingen Castle. In the extraordinary ambiance of the baroque palace, the ANKA and KNMF directorates (represented by Clemens Heske and Jürgen Mohr, respectively) welcomed almost 200 participants representing universities, research facilities, and companies from 10 different countries. The meeting was kicked off by KIT Chief Science Officer Volker Saile, who emphasized the positive developments and increase in user numbers at both facilities.     

Direct synthesis of inverse hexagonally ordered diblock copolymer/polyoxometalate nanocomposite films

Nanostructured inverse hexagonal polyoxometalate composite films were cast directly from solution using poly(butadiene-block-2-(dimethylamino)ethyl methacrylate) (PB-b-PDMAEMA) diblock copolymers as structure directing agents for phosphomolybdic acid (H(3)[PMo(12)O(40)], H(3)PMo). H(3)PMo units are selectively incorporated into the PDMAEMA domains due to electrostatic interactions between protonated PDMAEMA and PMo(3-) anions. Long solvophilic PB chains stabilized the PDMAEMA/H(3)PMo aggregates in solution and reliably prevented macrophase separation. The choice of solvent is crucial. It appears that all three components, both blocks of the diblock copolymer as well as H(3)PMo, have to be soluble in the same solvent which turned out to be tetrahydrofuran, THF. Evaporation induced self-assembly resulted in highly ordered inverse hexagonal nanocomposite films as observed from transmission electron microscopy and small-angle X-ray scattering. This one-pot synthesis may represent a generally applicable strategy for integrating polyoxometalates into functional architectures and devices.     

Model reduction for optimal control problems in field-flow fractionation

We discuss the application of model order reduction to optimal control problems governed by coupled systems of the Stokes-Brinkman and advection-diffusion equations. Such problems arise in field-flow fractionation processes for the efficient and fast separation of particles of different size in microfluidic flows. Our approach is based on a combination of balanced truncation and tangential interpolation for model reduction of the semidiscretized optimality system. Numerical results demonstrate the properties of this approach. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Comprehensive Two-Dimensional Gas Chromatography as a Powerful Strategy for the Exploration of Broas Volatile Composition

Broa is a Portuguese maize bread with characteristic sensory attributes that can only be achieved using traditional maize varieties. This study intends to disclose the volatile compounds that are mainly associated with the baking process of broas, which can be important contributors to their aroma. Twelve broas were prepared from twelve maize flours (eleven traditional maize varieties and one commercial hybrid). Their volatile compounds were analyzed by GC×GC–ToFMS (two-dimensional gas chromatography coupled with time-of-flight mass spectrometry) for an untargeted screening of the chemical compounds mainly formed during baking. It was possible to identify 128 volatiles that belonged to the main chemical families formed during this stage. Among these, only 16 had been previously detected in broas. The most abundant were furans, furanones, and pyranones, but the most relevant for the aroma of broas were ascribed to sulfur-containing compounds, in particular dimethyl trisulfide and methanethiol. Pyrazines might contribute negatively to the aroma of broas since they were present in higher amounts in the commercial broa. This work constitutes the most detailed study of the characterization of broas volatile compounds, particularly those formed during the Maillard reaction. These findings may contribute to the characterization of other maize-based foodstuffs, ultimately improving the production of foods with better sensory features.