The Separation of Platinum Group Metals (PGM) in Chloride Media by Isothiouronium Resins

Styrene-divinylbenzene copolymers incorporating isothiourea functional groups show a remarkable affinity for platinum-group-metal (PGM) ions in chloride media, The mode of ion binding to the resin depends on the equilibria between isothiourea (free base) form and isothiouronium (conjugated acid) form, This in return is related to matrix structure, A. resin, Monivex, which shows high binding capacities for PGM ions in high acidities (2–6M HC1) is described. Equilibrium, rate and selectivity data, as well as process application data is presented and discussed, Electron microprobe studies are used to follow chemical changes in resin beads and ion regeneration patterns.     

Reflections on the status and nature of visual reasoning - the case of the matches

This paper gives an interpretation of the transformation formulae (in matrix notation) for rotations in the plane in terms of the exponential function. Then the fact that the addition of two rotations corresponds to the multiplication of the corresponding matrices is given a simple interpretation.     

Ueber einige,bei Schwingungsproblemen auftretende,Differentialgleichungen

Ohne Zusammenfassung     

The application of optical coherence tomography to problems in polymer matrix composites

The Composites Group at the National Institute of Standards and Technology has found optical coherence tomography (OCT) to be a powerful tool for non-destructive characterization of polymer matrix composites. Composites often exhibit superior properties to traditional materials such as wood and metal. However, the barrier to their widespread infiltration into consumer markets is cost. Composites can be made more cost competitive by improved composite design, process optimization, and quality control. OCT provides a means of evaluating the three aforementioned areas. OCT is a very versatile technique that can be applied to a variety of problems in polymer composites such as: microstructure determination for permeability and mechanical property prediction, void, dry spot, and defect detection, and damage evaluation. Briefly, OCT uses a low coherence source such as a superluminescent diode laser with a fiber optic based Michelson interferometer. In this configuration, the composite is the fixed arm of the interferometer. Reflections from heterogeneities within the sample are mapped as a function of thickness for any one position. Volume information is generated by translating the sample on a motorized stage. Information about the location and size of a feature within the composite is obtained. In this work, the power of OCT for imaging composite microstructure and damage is presented. An example of permeability prediction using the composite microstructure imaged from OCT is demonstrated. The effect of image processing on the value of permeability is discussed. Using the same sample, OCT imaging of composite impact damage is compared to more traditional techniques, X-ray computed tomography and confocal microscopy.     

Synthesis of Multinuclear Pyridylimine Based Palladium(II) Complexes with a Functionalized Star Polystyrene Core and Evaluation of Their Catalytic Activity Towards Ethylene Oligomerization

Summary: The synthesis of a novel series of multi‐nuclear macroligated pyridylimine based palladium(II) complexes conjugated to a synthetic star polymer core has been well‐described. Star shaped polystyrene with a finite number of arms were prepared by atom transfer radical polymerization (ATRP) and the chain ends were chemically modified in order to introduce the desired end functionality. Utilizing this polymer as organic supports for pyridylimine‐based ligands, palladium(II) complexes were synthesized. On activating with methylaluminoxane (MAO), this complex showed substantially high activity towards ethylene oligomerization, producing C₄ and C₆ compositions as major products. The plausible mechanistic insight concerning the process of ethylene oligomerization is also broached.

An example of trinuclear pyridylimine based palladium(II) complex having a functionalized star polystyrene core.     

Electrochemical oxidation of molecular nitrogen to nitric acid – towards a molecular level understanding of the challenges

Nitric acid is manufactured by oxidizing ammonia where the ammonia comes from an energy demanding and non-eco-friendly, Haber–Bosch process. Electrochemical oxidation of N₂ to nitric acid using renewable electricity could be a promising alternative to bypass the ammonia route. In this work, we discuss the plausible reaction mechanisms of electrochemical N₂ oxidation (N₂OR) at the molecular level and its competition with the parasitic oxygen evolution reaction (OER). We suggest the design strategies for N₂ oxidation electro-catalysts by first comparing the performance of two catalysts – TiO₂(110) (poor OER catalyst) and IrO₂(110) (good OER catalyst), towards dinitrogen oxidation and then establish trends/scaling relations to correlate OER and N₂OR activities. The challenges associated with electrochemical N₂OR are highlighted.

Electrochemical oxidation of N₂ to HNO₃ (N₂OR) is explored in conjunction with parasitic oxygen evolution reaction (OER) on a poor and a good OER catalyst, TiO₂ and IrO₂. We develop scaling relations to correlate OER and N₂OR activities on oxides.