A radium assay technique using hydrous titanium oxide adsorbent for the Sudbury Neutrino Observatory

As photodisintegration of deuterons mimics the disintegration of deuterons by neutrinos, the accurate measurement of the radioactivity from thorium and uranium decay chains in the heavy water in the Sudbury Neutrino Observatory (SNO) is essential for the determination of the total solar neutrino flux. A radium assay technique of the required sensitivity is described that uses hydrous titanium oxide adsorbent on a filtration membrane together with a beta-alpha delayed coincidence counting system. For a 200 tonne assay the detection limit for 232Th is a concentration of 3 x 10^(-16) g Th/g water and for 238U of 3 x 10^(-16) g U/g water. Results of assays of both the heavy and light water carried out during the first two years of data collection of SNO are presented.Comment: 12 pages, 4 figure

Matching the nano- to the meso-scale: measuring deposit–surface interactions with atomic force microscopy and micromanipulation

Many researchers have studied the effects of changing the surface on fouling and cleaning. In biofouling the 'Baier curve' is a well-known result which relates adhesion to surface energy, and papers on the effect of changing surface energy to food fouling can be found more than 40 years ago. Recently the use of modified surfaces, at least at a research level, has been widespread. Here two different ways of studying surface-deposit interactions have been compared. Atomic force microscopy (AFM) is a method for probing interactions at a molecular level, and can measure (for example) the interaction between substrate and surfaces at a nm-scale. At a μm-mm level, we have developed a micromanipulation tool that can measure the force required to remove the deposit; the measure incorporates both surface and bulk deformation effects. The two methods have been compared by studying a range of model soils: toothpaste, as an example of a soil that can be removed by fluid flow alone, and confectionery soils. Removal has been studied from glass, stainless steel and fluorinated surfaces as examples of the sort of surfaces that can be found in practice. AFM measurements were made by using functionalized tips in force mode. The two types of probe give similar results, although the rheology of the soil affects the measurement from the micromanipulation probe under some circumstances. The data suggests that either method could be used to test candidate surfaces

Direct solid state NMR observation of the 105Pd nucleus in inorganic compounds and palladium metal systems

The ability to clearly relate local structure to function is desirable for many catalytically relevant Pd-containing systems. This report represents the first direct 105Pd solid state NMR measurements of diamagnetic inorganic (K2Pd(iv)Cl6, (NH4)2Pd(iv)Cl6 and K2Pd(iv)Br6) complexes, and micron- and nano-sized Pd metal particles at room temperature, thereby introducing effective 105Pd chemical shift and Knight shift ranges in the solid state. The very large 105Pd quadrupole moment (Q) makes the quadrupole parameters (CQ, ηQ) extremely sensitive to small structural distortions. Despite the well-defined high symmetry octahedral positions describing the immediate Pd coordination environment, 105Pd NMR measurements can detect longer range disorder and anisotropic motion in the interstitial positions. The approach adopted here combines high resolution X-ray pair distribution function (PDF) analyses with 105Pd, 39K and 35Cl MAS NMR, and shows solid state NMR to be a very sensitive probe of short range structural perturbations. Solid state 105Pd NMR observations of ∼44-149 μm Pd sponge, ∼20-150 nm Pd black nanoparticles, highly monodisperse 16 ± 3 nm PVP-stabilised Pd nanoparticles, and highly polydisperse ∼2-1100 nm biomineralized Pd nanoparticles (bio-Pd) on pyrolysed amorphous carbon detect physical differences between these systems based on relative bulk:surface ratios and monodispersity/size homogeneity. This introduces the possibility of utilizing solid state NMR to help elucidate the structure-function properties of commercial Pd-based catalyst systems. © 2018 the Owner Societies

Identification of an aquaculture poriferan "Pest with Potential" and its phylogenetic implications

Correct identification and classification of sponges is challenging due to ambiguousor misleading morphological features. A particular case is a blue keratose spongeoccasionally referred to as the ``Blue Photo Sponge'' among aquarists, which appearsfrequently (and in several cases unintended) in private aquaria. This spicule-less species,occasionally specified as Collospongia auris Bergquist, Cambie & Kernan 1990, not onlydisplays a high phenotypic plasticity in growth form and colour, it also proliferatesin aquacultures under standard conditions unlike most other sponges. Therefore, thisspecies is regarded as a pest for most aquarists. In turn, the ease of cultivation andpropagation in aquacultures qualifies this species as a model organism for a wide arrayof scientific applications. For these purposes, correct identification and classification areindispensable. We reconstructed ribosomal gene trees and determined this species asLendenfeldia chondrodes (De Laubenfels, 1954) (Phyllospongiinae), distant to Collospon-gia auris, and corroborated by skeletal features. Additionally, the resulting phylogenycorroborated major shortcomings of the current Phyllospongiinae classificationitsconsequences are discussed.<br