The provision of urban parks: an empirical test of spatial spillovers in an urban area using geographic information systems

Green spaces provide various amenities ranging from ecological services to recreational benefits. They are strategic for municipalities both for households and business attractiveness. While the social demand for urban parks is increasing, information about their provision and guidance regarding the efficiency of local policies remain scarce. In this paper, we investigate the existence and the nature of spatial spillovers for the provision of urban parks in 93 municipalities in the urban area of Angers, France. We use geographic information systems to obtain land use data. We estimate a reaction function, with interactions between cities and their provision of urban parks. For this end, we shall apply spatial econometric techniques. We find positive autocorrelation among municipalities. A 10% rise in the level of parks in neighboring municipalities leads to a 3.6% increase ceteris paribus. From the empirical perspective, we cannot reject the hypothesis of mimetic behaviour among municipalities.     

Optimization of the side-chain density to improve the charge transport and photovoltaic performances of a low band gap copolymer

Poor processability and low molecular weights are often hindering the efficient utilization of novel conjugated polymers in optoelectronic devices. Increasing the alkyl side-chain density generally enhances the polymer solubility but may affect as well its optoelectronic properties. In this work, we use density functional theory to identify ways to increase the side-chain density of donor-acceptor alternate copolymers based on 2,1,3-benzothiadiazole, thiophene and thieno[3,2-b]thiophene units, without modifying there otherwise promising frontier orbital energy levels. Following the theoretical results, a new polymer could be synthesized, exhibiting good processability and improved charge transport. As a consequence, the photovoltaic device performances of this polymer family could be enhanced, reaching a 3.7% power conversion efficiency in a standard device configuration and without any post-deposition treatment.     

Evaluation of the Chiral DIANANE Backbone as Ligand for Organolithium Reagents

Novel endo,endo‐2,5‐diaminonorbonane‐derived tertiary C₂‐symmetrical diamines were synthesized via the one‐pot reductive amination of enantiomerically pure norbornane‐2,5‐dione. These ligands were applied to various catalytic reactions such as asymmetric deprotonation, asymmetric bromine‐lithium exchange, and enantioselective addition of aryl‐ and allkylithium reagents to aromatic aldimines.     

Hydroxamic acids as potent inhibitors of Fe(II) and Mn(II) E. coli methionine aminopeptidase: biological activities and X-ray structures of oxazole hydroxamate-EcMetAP-Mn complexes

New series of acids and hydroxamic acids linked to five-membered heterocycles including furan, oxazole, 1,2,4- or 1,3,4-oxadiazole, and imidazole were synthesized and tested as inhibitors against the Fe(II) , Co(II) , and Mn(II) forms of E. coli methionine aminopeptidase (MetAP) and as antibacterial agents against wild-type and acrAB E. coli strains. 2-Aryloxazol-4-ylcarboxylic acids appeared as potent and selective inhibitors of the Co(II) MetAP form, with IC(50) values in the micromolar range, whereas 5-aryloxazol-2-ylcarboxylic acid regioisomers and 5-aryl-1,2,4-oxadiazol-3-ylcarboxylic acids were shown to be inefficient against all forms of EcMetAP. Regardless of the heterocycle, all the hydroxamic acids are highly potent inhibitors and are selective for the Mn(II) and Fe(II) forms, with IC(50) values between 1 and 2 μM. One indole hydroxamic acid that we previously reported as a potent inhibitor of E. coli peptide deformylase also demonstrated efficiency against EcMetAP. To gain insight into the positioning of the oxazole heterocycle with reversed substitutions at positions 2 and 5, X-ray crystal structures of EcMetAP-Mn complexed with two such oxazole hydroxamic acids were solved. Irrespective of the [metal]/[apo-MetAP] ratio, the active site consistently contains a dinuclear manganese center, with the hydroxamate as bridging ligand. Asp 97, which adopts a bidentate binding mode to the Mn2 site in the holoenzyme, is twisted in both structures toward the hydroxamate bridging ligand to favor the formation of a strong hydrogen bond. Most of the compounds show weak antibacterial activity against a wild-type E. coli strain. However, increased antibacterial activity was observed mainly for compounds with a 2-substituted phenyl group in the presence of the nonapeptide polymyxin B and phenylalanine-arginine-β-naphthylamide as permeabilizer and efflux pump blocker, respectively, which boost the intracellular uptake of the inhibitors.     

Optical transmission as a fast and non‐destructive tool for determination of ethylene‐co‐vinyl acetate curing state in photovoltaic modules

Poly(ethylene‐co‐vinyl acetate) (EVA) is the primary polymer used for encapsulation of photovoltaic (PV) modules. Its degree of cross‐linking (gel content) is taken as a major quality reference. The EVA gel content is normally measured by Soxhlet extraction and more recently also by Differential Scanning Calorimetry (DSC). The DSC method is proven here to be fast and effective but is, as the Soxhlet extraction method, destructive to the PV module. With the aim of developing a fast and non‐destructive method to determine the gel content, a number of analytical techniques are presented. The most promising method is ultraviolet/visible/near‐infrared (UV/Vis/NIR) optical transmission. The measured diffuse transmission reflects the EVA crystallite size, which is related to the EVA gel content. This opens the possibility to apply an in‐line analysis of every PV module immediately after the lamination step and could significantly contribute to the process quality control that is needed in future high‐throughput production lines of PV modules. Copyright © 2011 John Wiley & Sons, Ltd.     

Nano Design of Alumina Supported Monometallic Catalysts: A Promising Way to Improve the Selective Hydrogenation of Poly-Unsaturated Hydrocarbons

In the field of catalysis by metals, a new insight for the nanodesign of supported heterogeneous catalysts is the tailoring of metallic nanoparticles. In this work, well-faceted monometallic nanoparticles (Pd, Pt, Ni) exposing mostly the {111} crystallographic facet are obtained in aqueous solution and are deposited on an alumina support. The involved mechanisms of nanoparticles formation are determined and are evidenced to be different as a function of the nature of the metal. In the case of palladium the mechanism consists in an oriented attachment of palladium nanoparticles leading to the energetically most favourable stacking of nanoparticles, at the origin of the early differentiation of the nanoparticles shapes and of the formation of the well-faceted palladium nanoparticles. In the case of platinum, the mechanism seems to be a combination of aggregation of already reduced nuclei and direct reduction depending on the experimental conditions. In the case of the less reductible metal, nickel, well-faceted nanoparticles are not obtained during the synthesis and only a thermal activation under hydrogen can engender their formation. The impact of the {111} crystallographic facet for platinum and nickel is very important and induces a drastic increase of selectivity towards olefins formation with a selectivity close to the one of a palladium catalyst which is the most selective metal for the selective hydrogenation of poly-unsaturated hydrocarbons.     

Development and Characterization of Phytosterol-Enriched Oil Microcapsules for Foodstuff Application

Phytosterols are lipophilic compounds contained in plants and have several biological activities. The use of phytosterols in food fortification is hampered due to their high melting temperature, chalky taste, and low solubility in an aqueous system. Also, phytosterols are easily oxidized and are poorly absorbed by the human body. Formulation engineering coupled with microencapsulation could be used to overcome these problems. The aim of this study was to investigate the feasibility of encapsulating soybean oil enriched with phytosterols by spray-drying using ternary mixtures of health-promoting ingredients, whey protein isolate (WPI), inulin, and chitosan as carrier agents. The effect of different formulations and spray-drying conditions on the microencapsules properties, encapsulation efficiency, surface oil content, and oxidation stability were studied. It was found that spherical WPI-inulin-chitosan phytosterol-enriched soybean oil microcapsules with an average size below 50 μm could be produced with good encapsulation efficiency (85%), acceptable level of surface oil (11%), and water activity (0.2–0.4) that meet industrial requirements. However, the microcapsules showed very low oxidation stability with peroxide values reaching 101.7 meq O₂/kg of oil just after production, and further investigations and optimization are required before any industrial application of this encapsulated system.     

Some Remarks on the Equivalence between 2D and 3D Classical Snakes and Geodesic Active Contours

Recently, Caselles et al. have shown the equivalence between a classical snake problem of Kass et al. and a geodesic active contour model. The PDE derived from the geodesic problem gives an evolution equation for active contours which is very powerfull for image segmentation since changes of topology are allowed using the level set implementation. However in Caselles' paper the equivalence with classical snake is only shown for 2D images and 1D curves, by using concepts of Hamiltonian theory which have no meanings for active surfaces. This paper propose to examine the notion of equivalence and to revisite Caselles et al. arguments. Then a notion equivalence is introduced and shown for classical snakes and geodesic active contours in the 2D (active contour) and 3D (active surface) case.