41 research outputs found

    Taking SPARQL 1.1 extensions into account in the SWIP system

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    International audienceThe SWIP system aims at hiding the complexity of expressing a query in a graph query language such as SPARQL. We propose a mechanism by which a query expressed in natural language is translated into a SPARQL query. Our system analyses the sentence in order to exhibit concepts, instances and relations. Then it generates a query in an internal format called the pivot language. Finally, it selects pre-written query patterns and instantiates them with regard to the keywords of the initial query. These queries are presented by means of explicative natural language sentences among which the user can select the query he/she is actually interested in. We are currently focusing on new kinds of queries which are handled by the new version of our system, which is now based on the 1.1 version of SPARQL

    HDS of 4,6-dimethyldibenzothiophene over CoMoS supported mesoporous SiO2-TiO2 materials

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    TiO2 supported SBA-15 (xTi@SBA-15) materials with various high TiO2 loadings (x = 25, 50 and 70 wt%) have been used as support for impregnation of CoMo active phase for the hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene (46DMDBT) as model molecule representative of gazole cuts. Compared to CoMoS supported over pure commercial TiO2 and conventional Al2O3, a higher total activity was measured corresponding to the presence of isomerization and dismutation reactions due to Brönsted acidity of TiO2. However, the HDS activity remains higher using alumina as support. Moreover, the DDS pathway was found favored to the HYD one with sulfided CoMo supported over xTi@SBA-15 catalysts contrary with alumina as support

    Enantioselective Phytotoxicity of the Herbicide Imazethapyr on the Response of the Antioxidant System and Starch Metabolism in Arabidopsis thaliana

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    Background: The enantiomers of a chiral compound possess different biological activities, and one of the enantiomers usually shows a higher level of toxicity. Therefore, the exploration of the causative mechanism of enantioselective toxicity is regarded as one of primary goals of biological chemistry. Imazethapyr (IM) is an acetolactate synthase (ALS)-inhibiting chiral herbicide that has been widely used in recent years with racemate. We investigated the enantioselectivity between R- and S-IM to form reactive oxygen species (ROS) and to regulate antioxidant gene transcription and enzyme activity. Results: Dramatic differences between the enantiomers were observed: the enantiomer of R-IM powerfully induced ROS formation, yet drastically reduced antioxidant gene transcription and enzyme activity, which led to an oxidative stress. The mechanism by which IM affects carbohydrate metabolism in chloroplasts has long remained a mystery. Here we report evidence that enantioselectivity also exists in starch metabolism. The enantiomer of R-IM resulted in the accumulation of glucose, maltose and sucrose in the cytoplasm or the chloroplast and disturbed carbohydrates utilization. Conclusion: The study suggests that R-IM more strongly retarded plant growth than S-IM not only by acting on ALS, but also by causing an imbalance in the antioxidant system and the disturbance of carbohydrate metabolism wit

    A putative phosphatase, LSF1, is required for normal starch turnover in Arabidopsis leaves

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    [[sponsorship]]分子生物研究所[[note]]已出版;[SCI];有審查制度;具代表性[[note]]http://gateway.isiknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=Drexel&SrcApp=hagerty_opac&KeyRecord=0032-0889&DestApp=JCR&RQ=IF_CAT_BOXPLOT[[note]]http://gateway.isiknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=RID&SrcApp=RID&DestLinkType=FullRecord&DestApp=ALL_WOS&KeyUT=00027424660002

    Acidity study of X zeolites modified by nickel and/or chromium cations in the case of binary and ternary exchanges

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    International audienceA series of Ni(x)-, Cr(x) and CrNi(x)-exchanged X zeolites (x being the ion-exchange degree) was prepared and characterised by nitrogen adsorption, XRD. DTA/TGA and pyridine adsorption-desorption followed by IR spectroscopy. The objective is mainly to estimate quantitatively the number, strength and nature of acid sites and their dependence on the type of cation and its exchange level. A comparison between the binary and ternary exchanges was also established. The crystallinity and micropore volume losses were more significant for Cr(x)X and CrNi(x)X. The concentration of Lewis acid sites decreases with increasing the exchange degree for Cr(x)X and Ni(x)X, while it increases up to 39% for CrNi(x)X. An increase of the concentration of Bronsted sites was obtained. The fact that both the Lewis and Bronsted acidities markedly decrease between 423 and 623 K, proves that the available acid sites are overall weak. The pyridine desorption from the protonic sites is easier with CrNi(39)X than with Cr(39)X and Ni(40)X at 623 K, indicating a decrease in the strength in the case of ternary exchange. (C) 2012 Elsevier Inc. All rights reserved
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