Inverse problems for granulometries by erosion

Let us associate to any binary planar shape X the erosion curve _X defined by _X: r IR^XA(XrB), where A(X) stands for the surface area of X and XrB for the eroded set of X with respect to the ball rB of size r. Note the analogy to shape quantification by granulometry. This paper describes the relationship between sets X and Y verifying _X = _Y. Under some regularity conditions on X, _X is expressed as an integral on its skeleton of the quench function q _X(distance to the boundary of X). We first prove that a bending of arcs of the skeleton of X does not affect _X: quantifies soft shapes. We then prove, in the generic case, that the five possible cases of behavior of the second derivative _X characterize five different situations on the skeleton Sk(X) and on the quench function q _X: simple points of Sk(X) where q _Xis a local minimum, a local maximum, or neither, multiple points of Sk(X) where q _Xis a local maximum or not. Finally, we give infinitesimal generators of the reconstruction process for the entire family of shapes Y verifying _X = _Y for a given X.     

Enhancement of the interfacial transfer of iodine by chemical reaction

Enhancement of the air‐water interfacial transfer of I₂ by reaction with I^? was investigated in order to evaluate a mechanistic model. Separate systems for evaporation and absorption of I₂ were studied. The overall mass transfer coefficient increased from 2 × 10^?4 to 2.5 × 10^?3 cm/s as I^? concentration increased from 10^?4 to 10^?1 M. At I^? concentrations greater than 10^?1 M, the interfacial transfer of I₂ was gas‐side limited. The model gave a good representation of these results.     

Sample preparation method for the ER-CALUX bioassay screening of (xeno-)estrogenic activity in sediment extracts

The application of bioassays to assess the occurrence of estrogenic compounds in the environment is increasing in both a scientific and statutory context. The availability of appropriate validated methods for sample pre-treatment and analysis is crucial for the successful implementation of bioassays. Here, we present a sample preparation method for the bioassay screening of estrogenic activity in sediment with the in vitro Estrogen Receptor mediated Chemical Activated LUciferase gene eXpression (ER-CALUX) assay. The method makes use of an Accelerated Solvent (ASE) or Soxhlet extraction with a mixture of dichloromethane and acetone (3:1, v/v), followed by clean up of the extract by Gel Permeation Chromatography (GPC). Recoveries of a panel of 17 pollutants differing largely in physical-chemical properties from spiked sediment were determined and appeared to be on average about 86%. Furthermore, the estrogenic potencies of all test compounds were individually assessed by determination of concentration-response relationships in the ER-CALUX assay. Concentration dependent estrogenic potency was found for 14 of the 17 compounds, with potencies of about 10(5) to 10(7) fold lower than the natural estrogenic hormone 17beta-estradiol. Anti-estrogenic potency was assessed by testing combinations of estradiol and individual test compounds, but was found for none of the compounds. The low estrogenic activity of the test compounds in the spiking mixture was well recovered during GPC treatment of the pure mixture, but did not contribute significantly to the background estrogenic activity present in the spiked sediment. Application of the method to field samples showed that estrogenic activity can be found at different types of locations, and demonstrated that levels between locations may vary considerably over relatively short distances.     

Multiphase imaging of gas flow in a nanoporous material using remote-detection NMR

Pore structure and connectivity determine how microstructured materials perform in applications such as catalysis, fluid storage and transport, filtering or as reactors. We report a model study on silica aerogel using a time-of-flight magnetic resonance imaging technique to characterize the flow field and explain the effects of heterogeneities in the pore structure on gas flow and dispersion with 129Xe as the gas-phase sensor. The observed chemical shift allows the separate visualization of unrestricted xenon and xenon confined in the pores of the aerogel. The asymmetrical nature of the dispersion pattern alludes to the existence of a stationary and a flow regime in the aerogel. An exchange time constant is determined to characterize the gas transfer between them. As a general methodology, this technique provides insights into the dynamics of flow in porous media where several phases or chemical species may be present.     

Biological validation of a sample preparation method for ER-CALUX bioanalysis of estrogenic activity in sediment using mixtures of xeno-estrogens

The combined estrogenic effects of mixtures of environmental pollutants in the in vitro ER-CALUX (chemical activated luciferase gene expression) bioassaywere examined to biologically validate a sample preparation method for the analysis of estrogenic compounds in sediment. The method used accelerated solvent extraction (ASE) and gel permeation chromatography (GPC) and was validated with respect to recovery of biological response taking mixture effects into account. Four mixtures of three to six xenoestrogenic compounds (bisphenol A, 4-nonylphenol, (4,4'-dichlorodiphenyl)trichloroethane, (2,4'-dichlorodiphenyl)trichloroethane, dieldrin, 4-n-octylphenol, alpha-chlordane, dibutylphthalate, (4,4'-dichlorodiphenyl)dichloroethylene, and 2,4,5-trichlorobiphenyl) were prepared. Experimentally determined mixture effects were well described by the concept of concentration addition (CA), as expected for similarly acting compounds. Observed estradiol equivalence factors of the mixtures (on average 1.2 +/- 0.3) agreed very well with the value predicted according to CA. The sample preparation method was then applied to pure mixtures of standards and to sediment spiked with one of the mixtures. Recoveries of estrogenic compounds were estimated by determination of their mixture potencies in ER-CALUX and compared to the mixture effects predicted by CA. Recoveries of estrogenic activity were between 80 and 129%, indicating that the additive behavior of mixtures of xeno-estrogens is well conserved during sample preparation. Together with an average repeatability of 18.3%, low average limit of detection (2.6 +/- 1.8 pg of EEQ/ g), and coefficient of variance (3.5 +/- 3.3%),this demonstrated the suitability of the sample preparation method for the analysis of mixtures of (xeno-)estrogenic compounds in sediment with the ER-CALUX assay.     

舒曼集团总部

舒曼集团的新址选置优越,位于能俯瞰荷兰北部的A9高速公路边上,并与一个自然保护区相邻。作为一个独立建筑,它的每个侧面都有独特的特征和外观。建筑四角作了升高处理,为项目特殊的功能需要提供空间。     

Self‐Assembled Collagen Microparticles by Aerosol as a Versatile Platform for Injectable Anisotropic Materials

Extracellular matrices (ECM) rich in type I collagen exhibit characteristic anisotropic ultrastructures. Nevertheless, working in vitro with this biomacromolecule remains challenging. When processed, denaturation of the collagen molecule is easily induced in vitro avoiding proper fibril self‐assembly and further hierarchical order. Here, an innovative approach enables the production of highly concentrated injectable collagen microparticles, based on collagen molecules self‐assembly, thanks to the use of spray‐drying process. The versatility of the process is shown by performing encapsulation of secretion products of gingival mesenchymal stem cells (gMSCs), which are chosen as a bioactive therapeutic product for their potential efficiency in stimulating the regeneration of a damaged ECM. The injection of collagen microparticles in a cell culture medium results in a locally organized fibrillar matrix. The efficiency of this approach for making easily handleable collagen microparticles for encapsulation and injection opens perspectives in active tissue regeneration and 3D bioprinted scaffolds.     

Alternative precursor systems for the MOCVD of aluminium nitride and gallium nitride

Two alternative precursor systems have been investigated for the growth of AlN and GaN by MOCVD. The first involved the reaction between Me₃M (M(DOUBLE BOND)Al, Ga) and tert-butylamine (^tBuNH₂), whilst the second route involved the pyrolysis of single-source precursors such as Me₃M(NH₃) (M(DOUBLE BOND)Al, Ga) and [Me₂Ga(NH₂)]₃. Both routes proved suitable for the deposition of AlN thin films, and epitaxial AlN layers have been deposited on sapphire (0001) from Me₃Al(NH₃) without any added NH₃. Attempts to grow GaN from Me₃Ga/^tBuNH₂ mixtures or Me₃Ga(NH₃) were unsuccessful, leading to the deposition of Ga droplets, although GaN films containing a large excess of Ga were deposited by low-pressure MOCVD from the single-source precursor [Me₂Ga(NH₂)]₃.     

Nitrate leaching from organic and conventional arable crop farms in the Seine Basin (France)

In the Seine Basin, characterised by intensive arable crops, most of the surface and groundwater is contaminated by nitrate (NO₃ ^?). The goal of this study is to investigate nitrogen leaching on commercial arable crop farms in five organic and three conventional systems. In 2012–2013, a total of 37 fields are studied on eight arable crop rotations, for three different soil and climate conditions. Our results show a gradient of soil solution concentrations in function of crops, lower for alfalfa (mean 2.8 mg NO₃-N l^?1) and higher for crops fertilised after legumes (15 mg NO₃-N l^?1). Catch crops decrease nitrate soil solution concentrations, below 10 mg NO₃-N l^?1. For a full rotation, the estimated mean concentrations is lower for organic farming, 12 ± 5 mg NO₃-N l^?1 than for conventional farming 24 ± 11 mg NO₃-N l^?1, with however a large range of variability. Overall, organic farming shows lower leaching rates (14–50 kg NO₃-N ha^?1) than conventional farms (32–77 kg NO₃-N ha^?1). Taking into account the slightly lower productivity of organic systems, we show that yield-scaled leaching values are also lower for organic (0.2 ± 0.1 kg N kg^?1 N year^?1) than for conventional systems (0.3 ± 0.1 kg N kg^?1 N year^?1). Overall, we show that organic farming systems have lower impact than conventional farming on N leaching, although there is still room for progress in both systems in commercial farms.     

Ultra-fast quantum-well saturable absorber devices and their application to all-optical regeneration of telecommunication optical signals

We review recent advances in the investigation of vertical cavity saturable absorber devices and their use for the all-optical regeneration of telecommunication signals in ultra-long-haul transmission systems. Such devices are polarization-insensitive and operate as fully passive nonlinear optical elements. Two approaches for obtaining fast recovery absorber materials are described, relying upon ion irradiation or upon iron doping. The vertical micro-cavity devices are designed so as to optimize the switching contrast and the operating power. Their functional behaviour as extinction ratio amplifiers has been characterized and their optimal operating conditions have been determined. The potential application of these devices to all-optical regeneration has been investigated through numerical simulations and fully demonstrated in several long-distance transmission loop experiments, with results obtained at 10, 20 and 40 Gbit/s, showing significant improvements in system haul or operational margins. A four-channel fibered module has also been fabricated, as a perspective towards the development of wavelength division multiplexing (WDM) saturable absorber modules.