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.     

Characterization and reactivity of VMgO catalysts prepared by wet impregnation and sol–gel methods

This paper reports the study of physicochemical, surface, and catalytic properties of two series of VMgO catalysts prepared by two different methods: wet impregnation and sol–gel. The characterizations of the elaborated materials were performed using N₂-sorption (Brunauer, Emmett and Teller (BET)), X-ray diffraction, Raman, transmission electron microscopy–energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy analyses. The catalytic properties of the elaborated materials were investigated in the isopropanol decomposition reaction to determine their acid–base character and in the selective oxidation of n-butane to evaluate their dehydrogenation properties. The preparation method and vanadium content strongly affected the properties of our materials. The sol–gel method leads to smaller crystallite size, higher specific surface area, and uniform particle distribution compared to the impregnation one. Both impregnation and SG solids promote the formation of acetone, which is related to the presence of strong basic sites (O^2? species) on the catalytic exposed surface. The more pronounced basic character was obtained through the SG samples. The sol–gel samples exhibited the highest catalytic activity and C4-olefin selectivity in the partial oxidation of n-butane. Whatever the preparation procedure, the nature of surface oxygen species plays an important role in the orientation of catalytic performances.     

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.     

Fuzzy semantic tagging and flexible querying of XML documents extracted from the Web

The relational database model is widely used in real applications. We propose a way of complementing such a database with an XML data warehouse. The approach we propose is generic, and driven by a domain ontology. The XML data warehouse is built from data extracted from the Web, which are semantically tagged using terms belonging to the domain ontology. The semantic tagging is fuzzy, since, instead of tagging the values of the Web document with one value of the domain ontology, we propose to use tags expressed in terms of a possibility distribution representing a set of possible terms, each term being weighted by a possibility degree. The querying of the XML data warehouse is also fuzzy: the end-users can express their preferences by means of fuzzy selection criteria. We present our approach on a first application domain: predictive microbiology.     

Heroin purchasing is income and price sensitive.

Semi-structured interviews were used to assess behavioral economic drug demand in heroin dependent research volunteers. Findings on drug price, competing purchases, and past 30-day income and consumption, established in a previous study, are replicated. We extended these findings by having participants indicate whether hypothetical environmental changes would alter heroin purchasing. Participants (n = 109) reported they would significantly (p