Interfacial concentrations of chloride and bromide in zwitterionic micelles with opposite dipoles: experimental determination by chemical trapping and a theoretical description

Interfacial concentrations of chloride and bromide ions, with Li(+), Na(+), K(+), Rb(+), Cs(+), trimethylammonium (TMA(+)), Ca(2+), and Mg(2+) as counterions, were determined by chemical trapping in micelles formed by two zwitterionic surfactants, namely N-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (HPS) and hexadecylphosphorylcholine (HDPC) micelles. Appropriate standard curves for the chemical trapping method were obtained by measuring the product yields of chloride and bromide salts with 2,4,6-trimethyl-benzenediazonium (BF(4)) in the presence of low molecular analogs (N,N,N-trimethyl-propane sulfonate and methyl-phosphorylcholine) of the employed surfactants. The experimentally determined values for the local Br(-) (Cl(-)) concentrations were modeled by fully integrated non-linear Poisson Boltzmann equations. The best fits to all experimental data were obtained by considering that ions at the interface are not fixed at an adsorption site but are free to move in the interfacial plane. In addition, the calculation of ion distribution allowed the estimation of the degree of ion coverage by using standard chemical potential differences accounting for ion specificity.     

Impact of the analytical blank in the uncertainty evaluation of the copper content in waters by flame atomic absorption spectrometry

Chemical analysts use analytical blanks in their analyses, but seldom is this source of uncertainty evaluated. Generally, there is great confusion. Although the numerical value of the blank, in some situations, can be negligible, its source of uncertainty cannot be. This article discusses the uncertainty contribution of the analytical blank using a numerical example of the copper content in waters by flame atomic absorption spectrometry. The results indicate that the uncertainties of the analytical blank can contribute up to 50% when the blank sample is considered in this analysis, confirming its high impact. This effect can be primarily observed where the analyte concentration approaches the lower range of the analytical curve. Even so, the blank is not always computed. Therefore, the relevance of the analytical blank can be confirmed by uncertainty evaluation.     

On the Dynamic Interaction and Cross-Interaction of 2D Rigid Structures with Orthotropic Elastic Media Possessing General Principal Axes Orientation

A direct boundary element method (BEM) implementation for the dynamic interaction analysis in the frequency domain of 2D rigid structures with elastic orthotropic media is presented. The BEM implementation is based on non-singular full-space influence functions. The rigid structure response is obtained by applying equilibrium and kinetic compatibility conditions. The method is applied to the analysis of the dynamic response of a rigid tunnel in a half-space with various elasticity principal axes inclinations and to the analysis of two rigid rectangular galleries in a half space with various distances between them.     

Inclusion Complex between Local Anesthetic/2-hydroxypropyl-β-cyclodextrin in Stealth Liposome

The drugs delivery system in the treatment of diseases has advantages such as reduced toxicity, increased availability of the drug, etc. Therefore, studies of the supramolecular interactions between local anesthetics (LAs) butamben (BTB) or ropivacaine (RVC) complexed with 2-hydroxypropyl-β-cyclodextrin (HP-βCD) and carried in Stealth liposomal (SL) are performed. ¹H-NMR nuclear magnetic resonance (DOSY and STD) were used as the main tools. The displacements observed in the ¹H-NMR presented the complexion between LAs and HP-βCD. The diffusion coefficients of free BTB and RVC were 7.70 × 10⁻¹⁰ m² s⁻¹ and 4.07 × 10⁻¹⁰ m² s⁻¹, and in the complex with HP-βCD were 1.90 × 10⁻¹⁰ m² s⁻¹ and 3.64 × 10⁻¹⁰ m² s⁻¹, respectively, which indicate a strong interaction between the BTB molecule and HP-βCD (98.3% molar fraction and Ka = 72.279 L/mol). With STD-NMR, the encapsulation of the BTB/HP-βCD and RVC/HP-βCD in SL vesicles was proven. Beyond the saturation transfer to the LAs, there is the magnetization transfer to the hydrogens of HP-βCD. BTB and RVC have already been studied in normal liposome systems; however, little is known of their behavior in SL.     

Essential Conditions for the Full Synergy of Probability of Occurrence Distributions

In this contribution, we specify the conditions for assuring the validity of the synergy of the distribution of probabilities of occurrence. We also study the subsequent restriction on the maximal extension of the strict concavity region on the parameter space of Sharma–Mittal entropy measures, which has been derived in a previous paper in this journal. The present paper is then a necessary complement to that publication. Some applications of the techniques introduced here are applied to protein domain families (Pfam databases, versions 27.0 and 35.0). The results will show evidence of their usefulness for testing the classification work performed with methods of alignment that are used by expert biologists.     

Estimation of decoherence in electromechanical circuits

This letter presents a schematic circuit with capacitive coupling between the CPW Cavity Center Trace (resonated with electromagnetic mode) and the mechanical Nanoresonator mediated by Transmon, resulting in the Cross-Kerr electromechanical effect. Then we show the dynamics of quantum states, showing the generation of superposition states and bipartite entanglement of continuous variables through nonlinear quantum electrodynamics in the circuit. Finally, we calculated and estimated the parameter for mechanical outcome through phase measurements of the CPW Cavity Center Trace electromagnetic mode.     

Magnetic resonance studies of copper (II) sorbitol complex,in solution,reveal a supramolecular structure compatible to the crystal structure

Although the Cu²⁺-sorbitol complex [Cu²⁺-Sorb] structure in crystalline state has been determined by X rays, it is not known in solution, where most studies of this complex are performed. Therefore, the goal of this work was to obtain information about the structure of this complex in aqueous solution using nuclear magnetic resonance and electron paramagnetic resonance spectroscopies. The magnetic resonance results indicate that the complex is formed at approximately pH 12. In this pH the sorbitol ¹H relaxation times were so short (broad line) that was not possible to use standard nuclear magnetic resonance parameters (nuclear Overhauser effect and spin–spin coupling constants values) to solve the three-dimensional structure. However, valuable structural information about the complex in solution was obtained. The relaxation results indicate that the Cu²⁺ ions are buried in the structure and not accessible to solvent; the ¹H and ¹³C spectra shows strong paramagnetic shift effect indicating short distance between these nuclei and Cu²⁺ in the structure. No electron paramagnetic resonance signal was observed in pH 12 indicating strong Cu²⁺- Cu²⁺ dipolar interaction, compatible to Cu²⁺-Cu²⁺ distances measured in crystal, from 1.148 to 1.393 Angstroms. The complex self-diffusion coefficient (D) of 1.58 × 10⁻¹⁰ m²/s value, determined by Diffusion-Ordered Spectroscopy, is compatible to a molecular weight of 3–6 KDa. Therefore, these results corroborate that the [Cu²⁺-Sorb] complex is assembled in solution, at pH 12, with several structural parameters compatible to the toroidal hexadecacuprate supramolecular structure determined in solid state.     

Finite vibrational displacements in the Eckart—Sayvetz basis

Curvilinear internal coordinates are considered in terms of cartesian displacements in a molecule-fixed basis determined by the Eckart-Sayvetz conditions. The latter are interpreted as a set of restrictions on the metrics of the space and define cartesian displacements of “pure” vibrational character expanded to any order in terms of internal coordinates. Explicit expressions for expansion coefficients are given as a function of contravariant components of the metric tensor taken from existing table. A compact notation is proposed for anharmonic force constants, expansion coefficients of redundancies and coupling terms of the rotation—vibration hamiltonian.     

Spectrophotometric study of complex formation equilibria of Ni(II) ion with benzyl-, phenyl- and dibutyldithiocarbamates

Complex formation equilibria between Ni(II) with benzyldithiocarbamate, phenyldithiocarbamate and dibutyldithiocarbamate have been studied spectrophotometrically at (25±0.1)°C in 0.1M diethanolamine/diethanolamonium ionic strength and pH 8.8 that prevents ligand decomposition, frequent in acid medium. The stability constants and molar absorptivity coefficients have been evaluated for the three complex species obtained in each case.     

Carbon-13 EPR Hyperfine Interaction in the Complex [Rh(CN)6]in a KCl Host Lattice

The hyperfine interaction with¹³C in nonenriched [Rh(CN)₆]⁴⁻, in a KCl host lattice at 7 K, is measured by continuous-wave X- and Q-band electron paramagnetic resonance, allowing, for the first time, a comparative study of spin densities on the carbon of the axial cyanide in this complex and in the similar [Co(CN)₆]⁴⁻complex. From the experimental data corrected for dipolar interactions,A_iso= 79.80 × 10⁻⁴cm⁻¹andA_anis= 0.76 × 10⁻⁴cm⁻¹.