Dynamic Interfacial Tension Behavior of Water/Oil Systems Containing In situ-Formed Surfactants

Time-dependent interfacial tension (IFT) has been investigated for an interfacially reactive immiscible system composed of model-acidified oil and alkaline water. The acidified oil was composed of either lauric acid or linoleic acid dissolved in n-dodecane. Drop volume tensiometry was employed to measure the interfacial tension between the two phases. In the case of lauric acid, the IFT value was found to decrease sharply with increasing alkali concentration, even at low drop formation times. In the case of linoleic acid, the IFT decrease with the drop formation time was more gradual, especially at low alkali concentration. The rate of formation of the interfacial area was also found to be dependent on alkali concentration.     

Parallel synthesis of multi-branched oligosaccharides related to elicitor active pentasaccharide in rice cell based on orthogonal deprotection and glycosylation strategy

We describe a parallel and efficient synthesis of multi-branched oligosaccharides 3a-g based upon the structure of the phytoalexin elicitor active branched pentasaccharide 2. One-pot sequential orthogonal deprotection of tetrasaccharide 5 with three different protecting groups provided each of seven glycosyl acceptors 4a-g. Glycosylation of the acceptors 4a-g, followed by deprotection provided branched oligosaccharides 3a-g. All the reaction processes from scaffold 5 to 3a-g except for final hydrogenolysis were achieved utilizing an automated synthesizer in a parallel fashion.     

Control of the Properties of Carbon Nanotubes Synthesized by CVD for Application in Electrochemical Biosensors

Interest in carbon nanotubes (CNT) has grown at a very rapid rate in the last decade. Their interesting physical and chemical properties open attractive possibilities in many application areas. These properties depend on the process conditions during synthesis and on subsequent purification steps. Recent studies have demonstrated that CNT can promote the electron transfer of biomolecules. These exceptional properties make them attractive for use in electrochemical biosensors. Multi walled nanotubes have been synthesized by the Chemical Vapor Deposition (CVD) method using methane as a carbon source and Ni–Al₂O₃–SiO₂ as the catalyst. The influence of the variation of certain reaction parameters such as feed gas composition, catalyst mass, temperature and reaction time in the yield of the CVD process has been established. In addition, the structural and chemical characteristics of the CNTs have been studied and a purification process to eliminate the catalyst and amorphous carbon has been developed that involves a gaseous oxidative process and acid treatment. The efficiency of the purification step has been determined by analytical techniques. Atomic force microscopy, Raman scattering, thermogravimetric analysis, inductively coupled plasma atomic spectroscopy are the characterization techniques employed in this work.     

Aqueous mercury adsorption in a fixed bed column of thiol functionalized mesoporous silica

The aim of this work was to investigate the aqueous mercury adsorption in a fixed bed of mesostructured silica SBA-15 functionalized with propylthiol by co-condensation (SBA-15-SH). Powdered synthesized adsorbents were used to prepare pellets with sizes ranging from 0.5 to 1 mm. The physicochemical properties determined from N₂ adsorption and chemical analysis were compared for powder and pellets. Batch static experiments were carried out to obtain the equilibrium mercury adsorption isotherms, resulting that although the maximum adsorption capacity was reduced from powder to pellets, the materials maintained high efficiency for mercury removal even at very low aqueous metal concentration. Dynamic experiments were carried out in a fixed bed column by modifying the volumetric flow rate, bed length, inlet concentration, and amount of propylthiol groups incorporated to the adsorbent, and analyzing the temporal scale and the mercury adsorption capacities. The elution of the fixed bed was carried out chemically by circulating an aqueous 2 M hydrobromic acid stream for 2 h so achieving a complete recovery of the mercury previously adsorbed. Simplified dynamic equations of Bohart–Adams and Wolborska were used for modeling the breakthrough curves.     

Heuristic approaches for support vector machines with the ramp loss

Recently, Support Vector Machines with the ramp loss (RLM) have attracted attention from the computational point of view. In this technical note, we propose two heuristics, the first one based on solving the continuous relaxation of a Mixed Integer Nonlinear formulation of the RLM and the second one based on the training of an SVM classifier on a reduced dataset identified by an integer linear problem. Our computational results illustrate the ability of our heuristics to handle datasets of much larger size than those previously addressed in the literature.     

Quinonediimine‐Induced Oxidative Coupling of Organomagnesium Reagents

N,N′‐Diphenyl‐p‐benzoquinonediimine, a redox‐active unit of polyaniline, efficiently induced the oxidative homocoupling of various aryl‐ and vinylmagnesium reagents in suppressing the side reactions, such as 1,2‐ or 1,4‐addition reaction.     

Hyperspherical harmonics and the nuclear four-body problem

A method proposed earlier by Aguilera, Moshinsky, and Kramer, for adapting a system of translationally invariant four-particle harmonic oscillator functions to the symmetry of the permutation group S(4), is applied to hyperspherical harmonic functions depending on three relative vectors. Except for a few cases in which diagonalization of matrices is required, the method gives closed formulas for orthonormal sets of harmonic functions with good permutational symmetry. The matrix elements of S(4) permutations with respect to the harmonic functions are obtained.     

Coordination-induced branched self-assembly of porphyrins bearing two redox-active phenylenediamine chains

The porphyrins bearing two three-dimensionally regulated oligoaniline chains with terminal pyridyl groups were synthesized. The self-assembled branched polymer complex by introducing Zn(II) to the porphyrin was achieved in solution, which underwent dropcasting on the surface of mica to result in dome-like nanostructures.     

Novel series of 8H-quinazolino[4,3-b]quinazolin-8-ones via two Niementowski condensations

Efficient microwave-assisted multi-step synthesis of 8H-quinazolino[4,3-b]quinazolin-8-one was investigated. The synthesis involved two Niementowski condensations from anthranilic acids. Homogeneous or heterogeneous conditions were studied with the aim to develop convenient syntheses of the desired compounds.