Encapsulation and Ostwald Ripening of Au and Au–Cl Complex Nanostructures in Silica Shells

We report a general template strategy for rational fabrication of a new class of nanostructured materials consisting of multicore shell particles. Our approach is demonstrated by encapsulating Au or Pt nanoparticles in silica shells. Other superstructures of these hollow shells, like dimers, trimers, and tetramers can also be formed by nanoparticle‐mediated self‐assembly. We have also used the as‐prepared multicore Au–silica hollow particles to perform the first studies of Ostwald ripening in confined microspace, in which chloride was found to be an efficient mediating ligand. After treatment with aqua regia, Au–Cl complex is formed inside the shell, and is found to be very active under in situ transmission electron microscopy observations while confined in a microcell. This aspect of the work is expected to motivate further in situ studies of confined crystal growth.     

Knowledge management in production alliances

This paper develops a managerial model of production network organizations (PNOs), inter-firm alliances for product development and delivery, in which inter-firm network structure and knowledge management practices play a major role in venture performance. The paper addresses the issue of alignment between the adopted network structure, the scope of the joint production task, and consequent inter-firm information flow requirements, hypothesizing that venture performance is a joint function of network structure and task integration scope. In situations with a difficult alignment between the chosen network structure, joint task scope, and information flow requirements, knowledge management investments across the PNO are proposed as a moderating factor leading to improved venture performance. The paper demonstrates the proposed model with three case studies, providing preliminary verification of the key proposition that knowledge management interventions can mediate the impact of loose integrating structures for joint production ventures that are undertaking complex joint tasks.     

The effect of skull-pin insertion on cerebrospinal fluid pressure and cerebral perfusion pressure: influence of sufentanil and fentanyl

Directed delivery and distribution of anaesthetics (novocaine, lidocaine, trimecaine) immobilized on finely dispersed iron powders under the influence of an external magnetic field in body tissues of test animals have been studied. The data of emission spectral analysis relating to concentration of iron in soft and bone tissues of animals influenced by constant and alternating magnetic field on front and reverse sides over a period from 0 to 180 min are given.     

The role of carbon deposition on precious metal catalyst activity during dry reforming of biogas

Gold and palladium were supported on a mesoporous TiO₂ for total oxidation of volatile organic compounds (VOCs). Mesoporous high surface area titania support was synthesised using of Ti(OC₂H₅)₂ in the presence of CTMABr surfactant. After removing the surfactant molecules, 0.5 or 1.5 wt% of palladium and 1 wt% of gold were precipitated on the support by, respectively, wet impregnation and deposition–precipitation methods. The activity for toluene and propene total oxidation of the prereduced samples follows the same order: 0.5%Pd-1%Au/TiO₂ > 1.5%Pd/TiO₂ > 0.5%Pd/TiO₂ > 1%Au-0.5%Pd/TiO₂ > 1%Au/TiO₂ > TiO₂. Moreover, a catalytic comparison with samples based on a conventional TiO₂, shows the catalytic advantage of the mesoporous TiO₂ support. The promotional effect of gold added to palladium could be partly explained by small metallic particles (TEM), but meanly by metallic particles made up of Au-rich core with a Pd-rich shell. Moreover, the hydrogen TPR profile of 0.5%Pd-1%Au/TiO₂ shows only the signal attributed to small PdO particles. Gold also implies a protecting effect of the support under reduction atmosphere. Operando diffuse reflectance infrared fourier transform (DRIFT) spectroscopy was carried on and allowed to follow the VOCs oxidation and the formation of coke molecules, but also a metallic electrodonor effect to the adsorbed molecule which increases in the same order as the activity for oxidation reaction. The presence of coke after test was also shown by DTA–TGA by exothermic signals between 300 and 500 °C and by EPR (g = 2.003).     

Effect of channel fade rate on throughput of three GHARQ-II schemesover Rayleigh fading channel

The performance of three GHARQ-II schemes, based on punctured convolutional codes, used over a simulated Rayleigh fading channel subject to additive white Gaussian noise are compared. Various fade rates and signal to noise ratios are considered     

Turbine airfoil degradation in the persian gulf war

Helicopter turbine engines used in the Desert Shield and Desert Storm operations experienced excessive sand ingestion. Fine particles were able to bypass filters and proceed through the combustor or cooling gaspaths. The first-stage turbine vanes were impacted with viscous silicate particles, forming a deposit on the leading-edge root platform and resulting in overheating and oxidation. The chemistry of the raw sand determines that of the ingested powders, the deposits, and the material reactions.     

Functionalized Nanostructures with Liquid‐Like Behavior: Expanding the Gallery of Available Nanostructures

Recently, we have developed a novel family of functionalized nanostructures that exhibit liquid‐like behavior in the absence of solvents and preserve their nanostructure in the liquid state. The gallery of nanostructures developed so far includes functionalized silica and magnetic iron oxide nanoparticles, layer‐like organosilicate nanoparticles, polyoxometalate clusters, and organic–inorganic hybrid networks. In an effort to demonstrate the wider applicability of this concept and to provide a deeper insight into this class of materials, the present work cites additional paradigms of functionalized nanostructures with similar behavior as above. In one case, surface functionalization of anatase nanoparticles (TiO₂, an inorganic nanostructure) with a quaternary ammonium organosilane leads to ionically modified nanoparticles that, when electrostatically combined with a poly(ethylene glycol) (PEG)‐tailed sulfonate anion, exhibit liquid‐like behavior in the absence of solvents. In a different but quite interesting case of a bionanostructure, ion‐exchange functionalization of a DNA oligonucleotide with a PEG‐tailed quaternary ammonium cation leads to an easily separable liquid derivative with attractive features. These examples show the versatility of this concept over a range of nanostructures.     

Assessing terrestrial wildlife populations in the Toronto and Region Area of Concern

Beneficial use impairments (BUIs) under the Great Lakes Water Quality Agreement identify environmental issues requiring remedial action within the Great Lakes Areas of Concern (AOCs). We conducted this study to support the assessment of the wildlife component of BUI 3: degradation of fish and wildlife populations. We compared bird and amphibian (frogs and toads) data from the Toronto and Region Conservation Authority’s Terrestrial Long-term Monitoring Program in the Toronto and Region AOC to an adjacent, but otherwise similar, reference watershed, Duffins Creek. Twelve of 13 targets were met within the AOC for forest bird, wetland bird, meadow bird and amphibian populations based on averages of mean annual values at sites within the AOC that were within two standard deviations of averages at sites in the Duffins Creek reference watershed between 2008 and 2017. Even though wildlife populations within the AOC were within the normal range of variability expected from a reference watershed, they were often at lower levels than within the Duffins Creek reference watershed. In addition, forest bird and amphibian populations were negatively affected by urbanization within the AOC and meadow bird indices declined. We conclude that while wildlife populations within the AOC currently meet targets for BUI 3, they continue to be negatively impacted by numerous stressors that are primarily related to past and ongoing urbanization. Thus, continued restoration of wildlife habitat and protection of existing habitat within the AOC is highly recommended.