Trend in using TiO2 nanotubes as photoelectrodes in PEC processes for wastewater treatment

Photoelectrocatalytic (PEC) processes represent an effective way to exploit renewable energy in response to the sustainable development objectives. The synergy between photo and electrochemical processes inspired several papers and stimulated research toward new systems that could be increasingly adapted to work under visible or solar radiation, and with minimum bias potential. Since the first appearance of articles on PEC processes in the literature, titanium dioxide has been one of the most studied semiconductor materials: nanostructured electrodes have been especially considered such as nanotubes (NT), which are the main subject of the present article. The software VOSviewer is used to a preliminary analysis of metadata, related to the trend of the research on PEC processes; attention is then paid on the trend of NT-TiO₂ electrodes for application in wastewater treatment in the past year.     

The Construction of Open GdIII Metal–Organic Frameworks Based on Methanetriacetic Acid: New Objects with an Old Ligand

The preparation, X‐ray crystallography and magnetic investigation of the first examples of methanetriacetate (mta)‐containing lanthanide(III) complexes of formulae [Gd(mta)(H₂O)₃]_n ? 4 n H₂O ( 1 ) [Gd(mta)(H₂O)₃]_n ? 2 n H₂O ( 2 ) and [Gd₂(mta)₂(H₂O)₂]_n ? 2 n H₂O ( 3 ) are described herein. This tripodal ligand promotes the formation of 6³ networks; thus 1 consists of a honeycomb structure, whereas in 2 two of these layers are condensed to form a rare five‐connected two‐dimensional (4⁸6²) network. Compound 3 can be seen as an aggregation of 6³ layers leading to a three‐dimensional (6,6)‐connected binodal (4¹²6³)(4⁹6⁶)‐ nia net, in which the gadolinium(III) ions and the mta ligands act as octahedral and as trigonal prismatic nodes, respectively. The magnetic properties of 1 – 3 were investigated in the temperature range 1.9–300 K. A close fit to the Curie law ( 1 ) and weak either antiferro‐ [J=?0.0063(1) cm^?1 ( 2 )] or ferromagnetic [J=+0.0264(6) cm^?1 ( 3 )] interactions between the Gd^III ions are observed; the different exchange pathways involved [extended tris‐bidentate mta ( 1 ) and μ‐O(1);κ²O(1),O(2) ( 2 and 3 ) plus single syn–syn carboxylate‐mta ( 3 )] accounting for these magnetic features. The nature and magnitude of the magnetic interactions, between the Gd^III ions in 1 – 3 , agree with the small amount of data existing in the literature for these kind of bridges.     

Characterization of pristine and purified organobentonites

Pristine and purified Argel sodium bentonites were organically modified with quaternary ammonium and phosphonium surfactants by ion exchange reaction in order to investigate the effect of the chemical identity of the surfactant and of the clay purification procedure in the intercalation process, final structure and thermal stability of organobentonites. The bentonites were characterized by X-ray diffraction analysis, thermogravimetric analysis and Fourier transform infrared spectroscopy. The bentonite purification treatment and, especially, the chemical structure of surfactant affected the thermal behavior of the organobentonites. The phosphonium modified bentonites were thermally more stable than those modified with ammonium, particularly the purified bentonite. These results seem to be promising regarding to the potential application of phosphonium modified Argel bentonites for the melt processing preparation of nanocomposites with polymeric matrices requiring high processing temperatures.     

Mechanism of the organocatalyzed decarboxylative Knoevenagel-Doebner reaction. A theoretical study

We have investigated important intermediates and key transition states of the organocatalyzed Knoevenagel condensation using density functional theory and two different basis sets (6-31 G(d,p) and 6-311++G(2df,2pd)), both in gas phase and simulating the bulk solvent (pyridine) using the PCM method. Calculated structures for reactants, intermediates, and key transition states suggest that the secondary amine catalyst is essential, both for activating the aldehyde for nucleophilic attack, and in the possible decarboxylation pathways. The calculated results are shown to agree with available experimental information. On the basis of the results obtained, the studied mechanism may be important in the understanding of vinylphenol production during malting and brewing of wheat and barley grains.     

New pentacoordinated Schiff-base diorganotin(IV) complexes derived from nonpolar side chain α-amino acids

In this work we report the synthesis and spectroscopic characterization of twenty new pentacoordinated diorganotin(IV) compounds. These compounds have been prepared in good yields by multicomponent reactions (MCRs) of α-amino acids (isoleucine, leucine, methionine, phenylalanine and aminophenylacetic acid), 2,4-dihydroxybenzaldehyde, 2-hydroxy-4-methoxybenzaldehyde and either di-n-butyltin(IV) oxide or diphenyltin(IV) oxide. All compounds were characterized by IR spectroscopy, ¹H, ¹¹⁹Sn and ¹³C NMR spectroscopy and mass spectrometry. Each compound has a coordinative N→Sn bond and shows the expected ¹¹⁹Sn NMR chemical shift indicative of a pentacoordinated or hexacoordinated tin atom in CDCl₃ and DMSO-d₆, respectively. These compounds were also tested in tumoral cell lines, HeLa, HCT-15 and MCF-7, in order to evaluate the antiproliferative activity and to obtain the medial inhibitory concentrations (IC₅₀) values.     

Bio-inspired optimization of fuzzy logic controllers for robotic autonomous systems with PSO and ACO

In this paper we describe the use of bio-inspired optimization techniques, such as ant colony optimization and particle swarm optimization, for the design of optimal fuzzy logic controllers of autonomous wheeled mobile robots. The results obtained by the simulations with ant colony optimization and particle swarm optimization are statistically compared with previous optimization results obtained with genetic algorithms in order to find out the best optimization technique for a particular robotics problem.     

Exotic components of SO(p,q) surface group representations,and their Higgs bundle avatars

For semisimple Lie groups, moduli spaces of Higgs bundles on a Riemann surface correspond to representation varieties for the surface fundamental group. In many cases, natural topological invariants label connected components of the moduli spaces. Hitchin representations into split real forms, and maximal representations into Hermitian Lie groups, are the only previously know cases where natural invariants do not fully distinguish connected components. In this note we announce the existence of new such exotic components in the moduli spaces for the groups $\mathrm{SO}(p,q)$ with $2<p<q$. These groups lie outside formerly know classes of groups associated with exotic components.