Fast Synthesis of Substituted N‐Phenylanthranilic Acids Using Ullmann Condensation Under Microwave Irradiation in Dry Media

Substituted N‐phenylanthranilic acids using the Ullmann condensation under microwave irradiation in dry media were obtained in good yield and short reaction times.     

Synthesis of Mono N-Substituted Guanylthioureas

A convenient method for the synthesis of mono N-substituted guanylthioureas in reasonable yields from readily available starting materials has been developed. In contrast to the previously published method, the use of highly noxious hydrogen sulfide is avoided. The method allows the rapid preparation of guanylthioureas since the synthesis of each requires only a single step from a common intermediate, the S-methylated derivative of dithiobiuret.     

Rapid Legionella pneumophila determination based on a disposable core–shell Fe3O4@poly(dopamine) magnetic nanoparticles immunoplatform

A novel amperometric magnetoimmunoassay, based on the use of core–shell magnetic nanoparticles and screen-printed carbon electrodes, was developed for the selective determination of Legionella pneumophila SG1. A specific capture antibody (Ab) was linked to the poly(dopamine)–modified magnetic nanoparticles (MNPs@pDA-Ab) and incubated with bacteria. The captured bacteria were sandwiched using the antibody labeled with horseradish peroxidase (Ab-HRP), and the resulting MNPs@pDA-Ab-Legionella neumophila-Ab-HRP were captured by a magnetic field on the electrode surface. The amperometric response measured at −0.15 V vs. Ag pseudo-reference electrode of the SPCE after the addition of H₂O₂ in the presence of hydroquinone (HQ) was used as transduction signal. The achieved limit of detection, without pre-concentration or pre-enrichment steps, was 10⁴ Colony Forming Units (CFUs) mL⁻¹. The method showed a good selectivity and the MNPs@pDA-Ab exhibited a good stability during 30 days. The possibility of detecting L. pneumophila at 10 CFU mL⁻¹ level in less than 3 h, after performing a membrane-based preconcentration step, was also demonstrated.     

“Rising to the challenge”: using generalization in pattern problems to unearth the algebraic skills of talented pre-algebra students

This study focuses on the generalization methods used by talented pre-algebra students in solving linear and non-linear pattern problems. A qualitative analysis of the solutions of three problems revealed two approaches to generalization: recursive–local and functional–global. The students showed mental flexibility, shifting smoothly between pictorial, verbal and numerical representations and abandoning additive solution approaches in favor of more effective multiplicative strategies. Three forms of reflection aided generalization: reflection on commonalities in the pattern sequence’s structure, reflection on the generalization method, and reflection on the “tentative generalization” through verification of the pattern sequence. The latter indicates an intuitive grasp of the mathematical power of generalization. The students’ generalizations evinced algebraic thinking in the discovery of variables, constants and their mutual relations, and in the communication of these discoveries using invented algebraic notation. This study confirms the centrality of generalizations in mathematics and their potential as gateways to the world of algebra.     

Effect of X-ray $$\mu$$ μ CT Resolution on the Computation of Permeability and Dispersion Coefficient for Granular Soils

Transport in Porous Media - X-ray micro-computed tomography ( $$\mu$$ CT) can produce realistic 3D-images of the pore structure of a material. Extracting its geometry enables the computation of...     

[Ni(cod)2][Al(ORF)4], a Source for Naked Nickel(I) Chemistry

The straightforward synthesis of the cationic, purely organometallic Ni^I salt [Ni(cod)₂]⁺[Al(OR^F)₄]⁻ was realized through a reaction between [Ni(cod)₂] and Ag[Al(OR^F)₄] (cod=1,5‐cyclooctadiene). Crystal‐structure analysis and EPR, XANES, and cyclic voltammetry studies confirmed the presence of a homoleptic Ni^I olefin complex. Weak interactions between the metal center, the ligands, and the anion provide a good starting material for further cationic Ni^I complexes.     

Gemini amphiphilic pseudopeptides: synthesis and preliminary study of their self-assembling properties

The synthesis of a family of Gemini Amphiphilic Pseudopeptide (GAP) molecules by a reductive amination reaction has been carried out. The process is highly modular and can be efficiently performed with different pseudopeptidic diamines as well as aliphatic and aromatic aldehydes. Preliminary studies showed the abilities of the GAPs to self-assemble into supramolecular nanostructures.     

Cross-linked poly(2-hydroxyethylmethacrylate) films doped with 1,2-diaminoanthraquinone (DAQ) as efficient materials for the colorimetric sensing of nitric oxide and nitrite anion

A series of cross-linked poly(2-hydroxyethylmethacrylate) (polyHEMA) films doped with 1,2-diaminoanthraquinone (DAQ) are described. The synthesis of the DAQ-containing polymers does not require any previous derivatization of the diamine. The films can be used as solid-state colorimetric sensors for nitrite anion as well as for aqueous and gaseous nitric oxide. Polymers show no appreciable leaching of DAQ even after six months of storage in water.     

Continuous symmetry analysis of NMR chemical shielding anisotropy

Molecular symmetry is a key parameter which dictates the NMR chemical shielding anisotropy (CSA). Whereas correlations between specific geometrical features of molecules and the CSA are known, the quantitative correlation with symmetry--a global structural feature--has been unknown. Here we demonstrate a CSA/symmetry quantitative relation for the first time: We study how continuous deviation from exact symmetry around a nucleus affects its shielding. To achieve this we employed the continuous symmetry measures methodology, which allows one to quantify the degree of content of a given symmetry. The model case we use for this purpose is a population of distorted SiH(4) structures, for which we follow the (29)Si CSA as a function of the degree of tetrahedral symmetry and of square-planar symmetry. Quantitative correlations between the degree of these symmetries and the NMR shielding parameters emerge.