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Structural transitions, ion mobility, and conductivity in CsSbF 3 (H 2 PO 4 ) ( I ) have been investigated by the methods of 1 H, 19 F, 31 P NMR (including 1 H, 19 F, 31 P MAS NMR), DSC, X-ray diffraction, and impedance spectroscopy. It was found that the fundamental changes in 1 H, 19 F, 31 P NMR spectra (above 390 K) were associated with the formation of a crystalline disorder phase I with high ionic mobility in the proton and fluoride sublattices, as a result of a phase transition in the 400–420 K range. In the same temperature range, the transition of PO 2 (OH) 2 – anions from the "rigid lattice" to fast reorientations takes place. Above 430 K, there occurs a transition from the crystalline disordered phase to the amorphous one. The types of ion mobility in CsSbF 3 (H 2 PO 4 ) and its amorphous phase have been established and temperature ranges of their realization have been determined (150–450 K). According to the NMR data, the diffusion in the proton sublattice of the disordered crystalline and amorphous phases is preserved even at room temperature. The ionic conductivity in CsSbF 3 (H 2 PO 4 ) reaches the values of ~ 2.6 × 10 –4 S/cm in the temperature range 410–425 K and decreases down to ~ 2.0 × 10 –5 S/cm upon transition to the amorphous phase (435–445 K). [ABSTRACT FROM AUTHOR]

The interaction of monodisperse fluorescent carboxylated polystyrene colloids (25 nm and 1000 nm diameter) with a cut granodiorite surface (Grimsel granodiorite; Switzerland) and with acrylic glass is investigated both experimentally and numerically. Colloid transport experiments are conducted in a parallel plate type fracture flow cell with an aperture of 0.75 mm at pH 5 under low ionic strength (1 mM NaCl) and under laminar flow (7 mL/h) conditions. The study focuses on the effect of residence time, colloid size, collector material and fracture orientation on colloid retention. Long colloid residence times are achieved by stop-flow experiments. Using atomic force microscopy and, more specifically, the colloid probe technique surface roughness and force distance information of the collector material (granodiorite or acrylic glass) as a function of probe size (cantilever) are obtained. The experiments are modeled using COMSOL Multiphysics® (2-D numerical simulations). The experimental and the modeled results lead to the conclusion that large colloids (1000 nm diameter) undergo sedimentation and deposition on the surface during stop-flow. Collector interaction is not affected by the surface roughness variation. Contrariwise, for the investigated 25 nm colloids sedimentation does not play a role under the experimental conditions and collector interaction is triggered by surface inhomogeneities such as surface roughness. [ABSTRACT FROM AUTHOR]

The diffusion rate of water in dilute clay dispersions depends on particle concentration, size, shape, aggregation and water-particle interactions. As nontronite clay particles magnetically align parallel to the magnetic field, directional self-diffusion anisotropy can be created within such dispersion. Here we study water diffusion in exfoliated nontronite clay dispersions by diffusion NMR and time-dependant 1H-NMR-imaging profiles. The dispersion clay concentration was varied between 0.3 and 0.7 vol%. After magnetic alignment of the clay particles in these dispersions a maximum difference of 20% was measured between the parallel and perpendicular self-diffusion coefficients in the dispersion with 0.7 vol% clay. A method was developed to measure water diffusion within the dispersion in the absence of a magnetic field (random clay orientation) as this is not possible with standard diffusion NMR. However, no significant difference in self-diffusion coefficient between random and aligned dispersions could be observed. [ABSTRACT FROM AUTHOR]

Highlights: [•] Lozenge shape PS-b-PLLA single crystals with uniform size are prepared. [•] Isotropic–nematic transition occurs at low volume fraction for crystal suspensions. [•] The orientation of crystals in nematic phase varies with crystal size. [•] Ethanol can block the lateral attraction. [•] Composite single crystals lose the highly orientation-dependant lateral attraction. [Copyright &y& Elsevier]

Highlights: [•] Reorientation of sulfonic groups upon hydration in copolymer SPEEK-HQ membranes. [•] Membranes were hydrophobic in air, but hydrophilic in water. [•] Sulfonic groups aggregated within the dry membrane. [•] Upper and lower surfaces of a membrane exhibited different hydrophilic characters. [•] Membrane acidification process induced a more hydrophilic membrane surface. [ABSTRACT FROM AUTHOR]

Abstract: A modified Carr–Purcell–Meiboom–Gill (CPMG) sequence for sensitivity enhancement of dipolar coupled homonuclear spin pairs in static solid-state NMR is presented. The modified CPMG block uses the Hahn-solid–Hahn echo as basic element of the CPMG echo train to refocus the homonuclear dipolar coupling and chemical shift anisotropy. The new CPMG sequence is dubbed as Hahn-solid–Hahn Carr–Purcell–Meiboom–Gill (HSHCPMG). We demonstrate a gain in signal to noise ratio of approximately 4.2 using HSHCPMG sequence in double quantum filtered CP experiment for 5%-13C2–15N-glycine. The resulting gain in sensitivity in the spikelet spectrum does not compromise the anisotropic information that is available from static NMR lineshapes. As an example, relative orientation angles of chemical shift anisotropy tensors for the alpha and carbonyl carbons in glycine are determined from the 2D DOQSY experiment recorded with the HSHCPMG block in the acquisition dimension. The resultant relative orientation angles of the two CSA tensors are compared to those obtained from 2D DOQSY experiment acquired without sensitivity enhancement as well as to the data as available from single crystal NMR experiments. [Copyright &y& Elsevier]

Abstract: The influence of droplet orientation on the flow directed organization of nanoparticles in evaporating nanofluid droplets is important for the efficiency of foliar applied fertilizers and contamination adhesion to the exterior of buildings. The so called “coffee ring” deposit resulting from the evaporation of a sessile nanofluid drop on a hydrophilic surface has received much attention in the literature. Deposits forming on hydrophobic surfaces in the pendant drop position (i.e. hanging drop), which are of importance in foliar fertilizer and exterior building contamination, have received much less attention. In this study, the deposit patterns resulting from the evaporation of water droplets containing silica nanoparticles on hydrophobic surfaces orientated in the sessile or pendant configuration are compared. In the case of a sessile drop the well known coffee ring pattern surrounding a thin nanoparticle layer was formed. A deposit consisting of a thin coffee ring surrounding a bump was formed in the pendant position. A mechanism involving flow induced aggregation at the droplet waist, settling, orientation dependant accumulation within the drop and pinning of the contact line is suggested to explain the findings. Differences in the contact area and adhesion of deposits with surface orientation will affect the efficiency and rainfastness of foliar fertilizers and the cleanliness of building exteriors. [Copyright &y& Elsevier]