Ring‐opening metathesis copolymerization of cyclooctene and a carborane‐containing oxanorbornene

The incorporation of a silyl‐protected oxanorbornene imide carborane (SONIC) in polyethylene‐like materials is reported. These copolymers were obtained via ring‐opening metathesis copolymerization of (SONIC) and cyclooctene followed by hydrogenation with p‐toluenesulfonylhydrazide. The composition of the copolymer was varied by altering the feed ratio. Structural and thermal properties were investigated and compared with that of a model polymer so as to gauge the impact on the inclusion of the silyl‐functionalized carborane. An initial observation of the modification of the chain sequence upon changing solvent polarity is also discussed. Finally, the potential utilization of these materials as radiation shielding materials is mentioned. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2557–2563, 2010     

The skin barrier function: a micro‐PIXE study

Human body is perpetually subjected to environmental exposures as sun, natural, urban or industrial pollutions and societal exposures. Skin is the main physiological barrier facing to these different stresses; however its response mechanisms are still not well understood. Skin models are thus necessary to understand skin physiology and behavior in normal conditions or under stress. Because of the large natural interindividual variability and of some difficulties in obtaining human skin biopsies, we have been developing and characterizing different skin models such as reconstructed epidermis in vitro, native pigskin and human keratinocyte cells. These models allow us to study the mechanisms involved in ion homeostasis in correlation with structural organization and biological responses. In the present study, we have characterized the pig ear skin model using micro‐particle induced x‐ray emission (PIXE) analysis with the aim of evaluating the distribution of inorganic ions under normal or stress conditions together with the transepidermal penetration of external agents, such as aluminum oxides. The nuclear microprobe analysis allowed us to validate the culture conditions of the tissue and we have shown an alteration of the inorganic ion patterns after exposure to a chemical compound (sodium dodecyl sulfate) known for its deleterious effects on the barrier function. Finally, we have shown no transepidermal penetration of aluminum oxides after different exposures to cosmetic formulations. Copyright © 2009 John Wiley & Sons, Ltd.     

Infrared diffuse reflectance instrumentation and standards at NIST

A spectrophotometer system for spectral characterization of materials in the infrared has been built around a bench-top Fourier transform instrument. Its capabilities include the measurement of directional-hemispherical reflectance from 1 to 18 μm. The spectral reflectance measurement is performed with an integrating sphere with an incidence angle of 8°. Both relative and absolute measurements can be made. Several methods can be used to determine the absolute value of the directional-hemispherical reflectance of samples. The primary method used is independent of the integrating sphere theory and the requisite assumptions associated with its use. The calibration of a standard reference material (SRM) is described. This SRM has a reflectance value near 0.9 over the complete calibration range 2–18 μm. As part of the calibration procedure the spatial uniformity of the sphere throughput and the bi-directional reflectance distribution function (BRDF) of the SRM material are evaluated.     

DPSIR = A Problem Structuring Method? An exploration from the “Imagine” approach

The Drivers, Pressures, State, Impact and Response or DPSIR framework has been with us for over a decade now and it is widely used as a means to assess and measure and, eventually provide a guide to managing the environment. With its repertoire of diagnostic and analytical components the DPSIR can be argued to be a Problem Structuring Method or PSM. Criticisms of the framework abound but it has a resilience which is noteworthy. Some argue that DPSIR, by its nature, is a narrowly formulated, engineering device, incompatible with the multiple perspectives which human interaction in global ecology requires. Is there a value in DPSIR being more flexible in expression and experience of users? In this article it is shown how the DPSIR framework was applied within a multi-methodology approach called Imagine in a number of coastal management projects around the Mediterranean and in other contexts. The article argues that DPSIR, whilst admittedly limited in its scope and approach can, if applied in a participatory and systemic multi-methodology, combine with other tools and help to create outcomes of value to local populations.     

Synthesis and characterization of BaZrO3-doped YBa2Cu3O7−δ microtapes with improved critical current densities

We have recently demonstrated that through a sol–gel route, superconductor crystallization in the presence of simple biopolymers results in a drastic alteration of morphology, producing technologically useful nanowires and porous architectures. Morphological control is of the utmost importance to bulk high-temperature superconductors, as grain boundaries act as weak links in limiting the achievable critical current density (J_c). Here we show that, as expected, the incorporation of nanoparticulate barium zirconate (BaZrO₃) species into a biopolymer-mediated synthetic protocol for YBa₂Cu₃O_7?δ (Y123) leads to a significantly improved in-field J_c compared to that observed in a sample without BaZrO₃ additions. To ameliorate degradation of the BaZrO₃ species in this protocol, we demonstrate that by drawing the precursor sol into fibers, a microtape architecture is able to be formed, leading to lengthy, anisotropic structures having enhanced J_c through the retention of the BaZrO₃ species.     

Reliability Issues of LES-Related Approaches in an Industrial Context

Large-Eddy Simulation (LES), Detached-Eddy Simulation (DES) and Scale-Adaptive Simulation (SAS) are increasingly being used as engineering tools to predict the behaviour of complex industrial flows. Often the flows studied have not been examined previously and the required grid resolution is unknown. Industrial users studying these flows tend to be using commercial CFD codes and do not usually have access to high-performance computing facilities. Due to the significant computing times required, it is difficult to undertake systematic grid-dependence studies. There is therefore a risk that LES, DES and SAS will be performed using overly coarse grids which may lead to unreliable predictions. The present work surveys a number of practical techniques that provide a means of assessing the quality of the grid resolution in large-eddy simulations and related approaches. To examine the usefulness of these techniques, a gas release in a ventilated room is examined using DES and SAS. The grid resolution measures indicate that overall the grids used are relatively coarse. Both DES and SAS model predictions are found to be in poor agreement with experimental data compared to steady and unsteady Reynolds-averaged Navier–Stokes (RANS) results using the SST model. The SAS model also shows the greatest grid sensitivity of the four models tested. The work highlights the need for grid-dependence studies and the potential problems of using coarse grids.