Search results for "Bonding"

The ionic dependence of calcium efflux from guinea pig auricles.

1968

Über eine mangelnde Parallelität zwischen Ionenpumpenhemmung und Kontraktionskraftsteigerung

1964

Δ 5-Pregnen-3,20-dione-N,N'-ethylpyrrolidine-bisguanylhydrazone and Δ5-pregnen-3β-hydroxy-20-one-N,N'-ethyl-pyrrolidine-monoguanylhydrazone inhibit the activity of the ionic pump of cold-stored erythrocytes of guinea-pigs. The contractile force of isolated guinea-pig auricles is decreased by the mono-derivate and increased by the bis-derivate in spite of the similar action upon the pumping mechanism.

Quantitative structure-retention relationships for ionic and non-ionic compounds in biopartitioning micellar chromatography

2004

Quantitative structure–retention relationships, QSRRs, represent a powerful tool in chromatography. The objectives of QSRR studies are to predict the chromatographic retention behaviour of solutes based on their structural properties, to elucidate retention mechanisms, to optimize the separation of complex mixtures or to prepare experimental designs. In this paper, using the retention factors of 151 structurally unrelated solutes that cover a wide range of hydrophobicity, molecular size, hydrogen bonding properties and ionization degrees obtained in biopartitioning micellar chromatography (BMC) at different Brij35 micellar concentrations, several multivariate QSRR models are tested. It is d…

Stimulated 7^Li echo NMR spectroscopy of slow ionic motions in a solid electrolyte

2000

Abstract Lithium spin-alignment spectroscopy is presented as an NMR technique for studying slow translational motions in solid and solid-like ionic conductors. We employ phase cycling that allows to measure two-time translational correlation functions via the generation of a pure quadrupolar ordered state. Correlation functions of the crystalline electrolyte Li 3 Sc 2 (PO 4 ) 3 were recorded for times ranging from about 0.1 ms to more than 10 s, implying that translational diffusion coefficients smaller than 10 −20 m 2 /s become accessible.

Characterization and Decomposition of the Natural van der Waals SnSb2Te4 under Compression

2020

[EN] High pressure X-ray diffraction, Raman scattering, and electrical measurements, together with theoretical calculations, which include the analysis of the topological electron density and electronic localization function, evidence the presence of an isostructural phase transition around 2 GPa, a Fermi resonance around 3.5 GPa, and a pressure-induced decomposition of SnSb2Te4 into the high-pressure phases of its parent binary compounds (alpha-Sb2Te3 and SnTe) above 7 GPa. The internal polyhedral compressibility, the behavior of the Raman-active modes, the electrical behavior, and the nature of its different bonds under compression have been discussed and compared with their parent binary…

Distortions of [Sb2Cl10]4– Bioctahedra and Phase Transitions in the Chloroantimonate(III) (C3H5NH3)2[SbCl5]·(C3H5NH3)Cl

2007

Bis(allylammonium)pentachloroantimonate(III) - allylammonium chloride, (C3H5NH3)2[SbCl5] · (C3H5NH3)Cl, belongs to the chloroantimonate(III) organic-inorganic salts family. The DSC studies of this compound showed two anomalies at 181 K and at 223 K. Both are associated with phase transitions, which mainly occur due to ordering-disordering processes of the organic cations. Between 181 and 223 K the structure is incommensurate. The crystal structure was determined at 298 and 86 K. At both temperatures the crystal structure consists of (C3H5NH3)+ cations, anionic distorted [Sb2Cl10]4− units and isolated Cl− ions. In the room-temperature phase two out of three, and in the low-temperature phase …

ChemInform Abstract: Chemistry and Properties of Solids with the (NZP) Skeleton

2010

Abstract Solids with an [NZP] skeleton in their structure from a very broad family presenting very different properties with varying chemical composition. These properties range from radioactive nuclide immobilization and insulation to ionic and/or electronic conduction, extending to the field of very low thermal expansion among others. The open [NZP] skeleton provides the stability and flexibility necessary to form continuous ranges of solid solution, allowing the tailoring of the best composition-property-structure material. Chemical activity may become particularly high at the surface and absorption reactions and catalytic properties have the highest interest at present. In this paper, c…

Chemistry and properties of solids with the [NZP] skeleton

1993

Abstract Solids with an [NZP] skeleton in their structure from a very broad family presenting very different properties with varying chemical composition. These properties range from radioactive nuclide immobilization and insulation to ionic and/or electronic conduction, extending to the field of very low thermal expansion among others. The open [NZP] skeleton provides the stability and flexibility necessary to form continuous ranges of solid solution, allowing the tailoring of the best composition-property-structure material. Chemical activity may become particularly high at the surface and absorption reactions and catalytic properties have the highest interest at present. In this paper, c…

Sugar-induced stabilization of the monoolein Pn3m bicontinuous cubic phase during dehydration

2001

To explore the molecular mechanism of the protective function of sugars on cubic lipidic systems, the mesomorphic properties of the monoolein-water system, dehydrated in the presence of a series of sugars, have been studied by osmotic stress experiments. Two bicontinuous inverse cubic structures $(Pn3m$ and $\mathrm{Ia}3d)$ and a lamellar ${L}_{\ensuremath{\alpha}}$ phase form under dehydration in pure water. In sugar solutions, the $\mathrm{Pn}3m$ phase shows an extraordinary stability: as a function of sugar concentration, the lattice parameter decreases to very low values, but no phase transitions occur. Instead, the $\mathrm{Pn}3m$ to $\mathrm{Ia}3d$ phase transition is obtained by equi…

Efficient light-induced phase transitions in halogen-bonded liquid crystals

2016

Here, we present a new family of light-responsive, fluorinated supramolecular liquid crystals (LCs) showing efficient and reversible light-induced LC-to-isotropic phase transitions. Our materials design is based on fluorinated azobenzenes, where the fluorination serves to strengthen the noncovalent interaction with bond-accepting stilbazole molecules, and increase the lifetime of the cis-form of the azobenzene units. The halogen-bonded LCs were characterized by means of X-ray diffraction, hot-stage polarized optical microscopy, and differential scanning calorimetry. Simultaneous analysis of light-induced changes in birefringence, absorption, and optical scattering allowed us to estimate tha…