BASF NanoSelect? Technology: Innovative Supported Pd- and Pt-based Catalysts for Selective Hydrogenation Reactions

An innovative BASF catalyst manufacturing technology (NanoSelect?) is introduced which allows production of heterogeneous catalysts with excellent control over metal crystallite sizes. NanoSelect? technology enabled the development of Pd catalysts which are lead-free Lindlar catalyst replacements in alkyne-to-cis-alkene hydrogenations. NanoSelect? Pt catalysts showed excellent chemoselectivity in substituted nitro-arene hydrogenation reactions without build-up of hydroxylamine intermediates. All NanoSelect? produced catalysts show markedly higher activity per gram of metal leading to ten-fold less use of precious metal.     

Measure-Valued Variational Models with Applications to Diffusion-Weighted Imaging

We develop a general mathematical framework for variational problems where the unknown function takes values in the space of probability measures on some metric space. We study weak and strong topologies and define a total variation seminorm for functions taking values in a Banach space. The seminorm penalizes jumps and is rotationally invariant under certain conditions. We prove existence of a minimizer for a class of variational problems based on this formulation of total variation and provide an example where uniqueness fails to hold. Employing the Kantorovich–Rubinstein transport norm from the theory of optimal transport, we propose a variational approach for the restoration of orientation distribution function-valued images, as commonly used in diffusion MRI. We demonstrate that the approach is numerically feasible on several data sets.     

Observation of Sublattice Disordering of the Catalytic Sites in a Complex Mo–V–Nb–Te–O Oxidation Catalyst Using High Temperature STEM Imaging

A Mo–V–Nb–Te–O oxidation catalyst has been imaged using scanning transmission electron microscopy at 780 K, which is slightly above its operating temperature. We observe a sublattice disordering of the corner-sharing octahedra forming the catalytic sites containing V⁵⁺ while the edge-sharing pentagonal bipyramidal {Nb(Mo₅)} sublattice remains structurally more rigid and thereby maintains the overall structural integrity of the catalyst. Imaging the termination of the edges of the [001] basal zones at room temperature reveal a preference for presence of a closed network of secondary structural {Nb(Mo)₅} units providing further evidence of the stability of this sublattice structure. We propose that sublattice disordering of catalytic sites enables structural flexibility to accommodate different oxidation states during multistep chemical reactions within a more rigid superstructure and presents a new paradigm for compositionally and structurally complex catalysts.     

Role of salt on adhesion of an epoxy/aluminum (oxide) interface in aqueous environments

Joints held by polymeric adhesives are commonplace in many engineered products, but normal service can require exposure to environmental conditions that present a significant challenge for maintaining the structural integrity of the interface. In particular, aqueous environments can wreak havoc on the joint strength. Here, a mechanistic approach is used to understand the difference in the debonding behavior of an epoxy/aluminum (oxide) interface when exposed to deionized (DI) water and aqueous sodium chloride by correlating macroscopic failure with the sorption of salt and water into the adhesive and its nanoscale distribution. For the epoxy‐aluminum system examined here, the presence of sodium chloride increases the resistance to crack growth in comparison to DI water. The debonding appears to be controlled by water near the buried interface. Salt water decreases the solubility of water in the epoxy and decreases the concentration of water near the buried interface, but the concentration of salt that enters the epoxy is below the detection limit. Thus, even if ions cannot penetrate or sorb into the adhesive, the presence of salt can significantly alter the water distribution within the adhesive and ultimately the strength of the joint. POLYM. ENG. SCI., 56:18–26, 2016. © 2015 Society of Plastics Engineers     

Reduction of the elongation at break of thermoplastic polyolefins through melt blending with polylactide and the influence of the amount of compatibilizers and the viscosity ratios of the blend components on phase morphology and mechanics

The objective of this work is the synthesis of a polypropylene/ethylene‐propylene‐rubber (TPO)/polylactide (PLA)/compatibilizer (PVM) blend to reduce the elongation at break of TPO by blending TPO with brittle PLA. Three TPO types with different viscosities were melt blended with PLA and an ethylene/n‐butylacrylate/glycidyl methacrylate terpolymer (PVM) as reactive compatibilizer. All blends had a constant PLA amount of 30 wt%. Two parameters were varied in the experiments, viscosity of the TPO types, and amount of PVM used in the blends. Both parameters played important roles in reducing the nominal elongation at break compared to pure TPO foils and influencing the phase morphology of extruded blend foils. The nominal elongation at break could be reduced by 100‐150% through blending TPO with PLA and PVM. Characterization regarding the blend morphology, especially the size and shape of the dispersed PLA phase in the TPO matrix was done by Environmental Scanning Electron Microscopy (ESEM) images. Investigations of the morphology showed that size and shape of dispersed PLA phases are dependent on the viscosity ratios of the blend components and on the amount of compatibilizer in the blend. AFM images of the polymer blends reveal soft rubbery layers around the dispersed PLA phases. POLYM. ENG. SCI., 56:905–913, 2016. © 2016 Society of Plastics Engineers     

Chemical Ecology of the host searching behavior in an Egg Parasitoid: are Common Chemical Cues exploited to locate hosts in Taxonomically Distant Plant Species?

Parasitoids are known to exploit volatile cues emitted by plants after herbivore attack to locate their hosts. Feeding and oviposition of a polyphagous herbivore can induce the emission of odor blends that differ among distant plant species, and parasitoids have evolved an incredible ability to discriminate them and locate their hosts relying on olfactive cues. We evaluated the host searching behavior of the egg parasitoid Cosmocomoidea annulicornis (Ogloblin) (Hymenoptera: Mymaridae) in response to odors emitted by two taxonomically distant host plants, citrus and Johnson grass, after infestation by the sharpshooter Tapajosa rubromarginata (Signoret) (Hemiptera: Cicadellidae), vector of Citrus Variegated Chlorosis. Olfactory response of female parasitoids toward plants with no herbivore damage and plants with feeding damage, oviposition damage, and parasitized eggs was tested in a Y-tube olfactometer. In addition, volatiles released by the two host plant species constitutively and under herbivore attack were characterized. Females of C. annulicornis were able to detect and significantly preferred plants with host eggs, irrespectively of plant species. However, wasps were unable to discriminate between plants with healthy eggs and those with eggs previously parasitized by conspecifics. Analysis of plant volatiles induced after sharpshooter attack showed only two common volatiles between the two plant species, indole and β-caryophyllene. Our results suggest that this parasitoid wasp uses common chemical cues released by many different plants after herbivory at long range and, once on the plant, other more specific chemical cues could trigger the final decision to oviposit.

     

Demonstration of the monolithic interconnection on CIS solar cells by picosecond laser structuring on 30 by 30 cm2 modules

In this paper, we present the selective structuring of all three patterns (P1, P2 and P3) of a monolithic interconnection of CIS (Cu(In,Ga)(S,Se)₂) thin film solar cells by picosecond laser pulses at a wavelength of 1064 nm. We show results for single pulse ablation threshold values and line scribing of molybdenum films on glass (P1), CIS on molybdenum (P2) and zinc oxide on CIS (P3). The purposes of these processes are the p‐type isolation (P1), cell interconnect (P2) and n‐type isolation (P3), which are required for complete cell architecture. The half micron thick molybdenum back electrode can be structured with a process speed of more than 15 m/s at about 15 W average power without detectable residues and damage by direct induced laser ablation from the back side (P1). The CIS layer can be structured selectively down to the molybdenum at process speeds up to 1 m/s at about 15 W average power, due to the precision of direct laser ablation in the ultrashort pulse regime (P2). The ZnO front electrode layer is separated by clean trenches with straight side walls at process speeds of up to 15 m/s at about 10 W average power, as a result of indirect induced laser ablation (P3). A validation of functionality of all processes is demonstrated on CIS solar cell modules (30 × 30 cm²). By replacing one state‐of‐the‐art process by a picosecond laser process at a time, solar efficiencies could be increased for P1 and P2 and stayed on a similar level for P3. After an optimization of the patterning processes in the R&D pilot line of AVANCIS, we achieved a new record efficiency for an all‐laser‐patterned CIS solar module: 14.7% as best value for the aperture area efficiency of a 30 × 30 cm² sized CIS module was reached. Copyright © 2014 John Wiley & Sons, Ltd.