Emulsions stabilised by food colloid particles: role of particle adsorption and wettability at the liquid interface

We study the effect of the particle wettability on the preferred type of emulsion stabilised solely by food colloid particles. We present results obtained with the recently developed gel trapping technique (GTT) for characterisation of wettability and surface structuring of individual food colloid particles adsorbed at air-water and oil-water interfaces. This method allows us to replicate a particle monolayer onto the surface of polydimethylsiloxane (PDMS) without altering the position of the particles. By observing the polymer surface with scanning electron microscopy (SEM), we are able to determine the contact angle of the individual particles at the initial liquid interface. We demonstrate that the GTT can be applied to fat crystal particles, calcium carbonate particles coated with stearic acid and spray-dried soy protein/calcium phosphate particles at air-water and oil-water interfaces. Subsequently, we prepare emulsions of decane and water stabilised by the same food colloid particles and correlate the wettability data obtained for these particles to the preferred type of emulsions they stabilise.     

Ending Aging in Super Glassy Polymer Membranes

Aging in super glassy polymers such as poly(trimethylsilylpropyne) (PTMSP), poly(4‐methyl‐2‐pentyne) (PMP), and polymers with intrinsic microporosity (PIM‐1) reduces gas permeabilities and limits their application as gas‐separation membranes. While super glassy polymers are initially very porous, and ultra‐permeable, they quickly pack into a denser phase becoming less porous and permeable. This age‐old problem has been solved by adding an ultraporous additive that maintains the low density, porous, initial stage of super glassy polymers through absorbing a portion of the polymer chains within its pores thereby holding the chains in their open position. This result is the first time that aging in super glassy polymers is inhibited whilst maintaining enhanced CO₂ permeability for one year and improving CO₂/N₂ selectivity. This approach could allow super glassy polymers to be revisited for commercial application in gas separations.     

Cu(0) nanoclusters derived from poly(propylene imine) dendrimer complexes of Cu(II).

A family of diaminobutane core, poly(propylene imine) dendrimers coordinated to Cu(II), DAB-Am(n)-Cu(II)x (n = 4, 8, 16, 32, 64, x = n/2), was studied by means of extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES) spectroscopies. The geometry of the dipropylene triamine (dpt)-Cu(II) end-group complexes for all dendrimer generations is reported for the first time and is found to be that of a square-based pyramid with each Cu ion bound to three nitrogen atoms (Cu-N distance approximately 2.03 A) of the dpt end group of the dendrimer. An oxygen atom residing 1.96 A from the Cu ion also occupies the equatorial plane, and the pyramid is completed by an axial oxygen at approximately 2.65 A. In addition, we report for the first time that reduction of the Cu(II)-dendrimer complexes with NaBH4 yields DAB-Am(n)-Cu(0)(cluster) species. Transmission electron microscopy (TEM) studies of the reduced species demonstrate that there is a systematic decrease in the size of the generated Cu clusters with increasing dendrimer generation. Additionally, it was found that the size of the nanoclusters is a function of the n/x ratio of the DAB-Am(n)-Cu(II)x precursor, with highly monodisperse, extremely small nanoclusters (r(cluster) = 8.0 +/- 1.6 A) obtained with n = 64 and x = 16. EXAFS and XANES measurements on the reduced DAB-Am(n)-Cu(0)(cluster) corroborate the TEM data, and provide additional information on the possible encapsulation of the Cu nanoclusters by the dendrimers.     

Neutrino observations from the sudbury neutrino observatory

Neutrino observations from the Sudbury Neutrino Observatory are presented from preliminary analyses. Based on energy, direction and location, the data in the region of interest appear to be dominated by ⁸B solar neutrinos, detected by the charged current reaction on deutrium and elastic scattering from electrons, with very little background. Measurements of radioactive backgrounds indicate that the measurement of all active neutrino types via the neutral current reaction on deuterium will be possible with small systematic uncertainties. Results for the fluxes observed with these reactions will be provided when further calibrations have been completed.     

Set mechanism in the lithium aluminum deuteride reduction of chloroadamantanes,and its induction by remote substituents

The title reduction may lead to very incomplete isotopic substitution as a result of SET intrusion and the related intermediacy of radicals and hydrogen abstraction from the solvent, even though the halogen to be replaced is chlorine. Two examples are reported. In one of them, this mechanism is shown to be induced through five single bonds by an ether substituent separated from the chlorine by a rigid W-chain of saturated carbons.