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Junting Feng - One of the best experts on this subject based on the ideXlab platform.
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coordinately unsaturated o2c ti5c o2c sites promote the reactivity of pt tio2 catalysts in the solvent free oxidation of n octanol
Catalysis Science & Technology, 2021Co-Authors: Pengfei Yang, Mark Douthwaite, Jiahao Pan, Lirong Zheng, Song Hong, David J Morgan, Mingyu Gao, Junting FengAbstract:A series of TiO2 anatase materials were synthesized with varying proportions of exposed (101) and (001) facets. Pt was subsequently impregnated onto these materials, which were then exposed to either an aerobic or reductive thermal treatment. The final catalysts were assessed for their performance in the aerobic, solvent free oxidation of octanol. Many kinds of characterization methods were employed to gain insight on how the exposed support facets influenced the catalysis. Thermal reduction of the catalysts led to a loss in the support surface structure, but in the contrary, after calcination, the defined facets remained, which was revealed by Raman and XRD. We further provide evidence that the coordinately unsaturated O2c–Ti5c–O2c sites present in the support promoted the dispersion of Pt after calcination in air, leading to the formation of low-coordinated and electron-deficient Pt clusters, based on high resolution- and spherical- aberration corrected transmission electron microscopy and X-ray absorption fine structure analysis. The calcined catalysts were far more active for both the oxidation of octanol and intermediate Octanal, thus resulting in a higher selectivity of octanoic acid. Catalyst performance closely correlated with the proportion of low-coordinated Pt species and the specific surface coordination structure of the support in the catalyst. Subsequent in situ Fourier transfer infrared experiments, conducted using alcohol and aldehydic probe molecules, confirmed that substrate adsorption was strongly influenced by the low-coordinated sites of both the Pt cluster and the exposed surface facets on the support.
Gerhard Gries - One of the best experts on this subject based on the ideXlab platform.
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identification of the larval aggregation pheromone of codling moth cydia pomonella
Journal of Chemical Ecology, 2005Co-Authors: Zaid Jumean, Regine Gries, Thomas R Unruh, Eloise Rowland, Gerhard GriesAbstract:Mature larvae of the codling moth, Cydia pomonella L. (Lepidoptera: Olethreutidae), exit the fruit and seek sites suitable for pupation. Spinning cocoons in such sites, larvae produce a complex, cocoon-derived blend of volatiles recently shown to attract and/or arrest both conspecific larvae and the prepupal parasitoid Mastrus ridibundus Gravenhorst (Hymenoptera: Ichneumonidae). Here we report components of this blend that constitute the pheromone of fifth-instar C. pomonella larvae. Thirty-one two-choice olfactometer experiments showed that a blend of synthetic (E)-2-octenal, (E)-2-nonenal, sulcatone, and geranylacetone, in combination with either 3-carene and/or three saturated aldehydes (Octanal, nonanal, decanal), elicited behavioral responses from C. pomonella larvae. In on-tree experiments with corrugated cardboard bands as pupation sites for larvae affixed to tree trunks, and with laboratory-reared larvae released onto such trees, more larvae cocooned in those halves of cardboard bands baited with cocoon-spinning conspecific larvae, or with synthetic pheromone components, than in unbaited control halves of the bands. With the larval aggregation pheromone identified in this study, there might be an opportunity to manipulate C. pomonella larvae in commercial fruit or nut orchards.
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Mastrus ridibundus parasitoids eavesdrop on cocoon-spinning codling moth, Cydia pomonella, larvae
Naturwissenschaften, 2005Co-Authors: Zaid Jumean, Tom Unruh, Regine Gries, Gerhard GriesAbstract:Cocoon-spinning larvae of the codling moth, Cydia pomonella L. (Lepidoptera: Olethreutidae) employ a pheromone that attracts or arrests conspecifics seeking pupation sites. Such intraspecific communication signals are important cues for illicit receivers such as parasitoids to exploit. We tested the hypothesis that the prepupal C. pomonella parasitoid Mastrus ridibundus Gravenhorst (Hymenoptera: Ichneumonidae) exploits the larval aggregation pheromone to locate host prepupae. In laboratory olfactometer experiments, female M. ridibundus were attracted to 3-day-old cocoons containing C. pomonella larvae or prepupae. Older cocoons containing C. pomonella pupae, or larvae and prepupae excised from cocoons, were not attractive. In gas chromatographic-electroantennographic detection (GC-EAD) analyses of bioactive Porapak Q extract of cocoon-derived airborne semiochemicals, ten compounds elicited responses from female M. ridibundus antennae. Comparative GC-mass spectrometry of authentic standards and cocoon-volatiles determined that these compounds were 3-carene, myrcene, heptanal, Octanal, nonanal, decanal, ( E )-2-octenal, ( E )-2-nonenal, sulcatone, and geranylacetone. A synthetic 11-component blend consisting of these ten EAD-active compounds plus EAD-inactive (+)-limonene (the most abundant cocoon-derived volatile) was as effective as Porapak Q cocoon extract in attracting both female M. ridibundus and C. pomonella larvae seeking pupation sites. Only three components could be deleted from the 11-component blend without diminishing its attractiveness to M. ridibundus , which underlines the complexity of information received and processed during foraging for hosts. Mastrus ridibundus obviously “eavesdrop” on the pheromonal communication signals of C. pomonella larvae that reliably indicate host presence.
Cristina Nerin - One of the best experts on this subject based on the ideXlab platform.
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compounds responsible for off odors in several samples composed by polypropylene polyethylene paper and cardboard used as food packaging materials
Food Chemistry, 2020Co-Authors: Paula Vera, Elena Canellas, Cristina NerinAbstract:Seven commercial samples, consisted of plastic bags, tetrabrik and box, were evaluated by gas chromatography-olfactometry-mass spectrometry (GC-O-MS) to find the compounds responsible for off-odors in different PP, PE, multilayer cardboard and paper materials used for food contact. Migration assays were carried out with Tenax as food simulant to analyze the food safety as well as to evaluate the odor intensity after migration assay. Forty six compounds with characteristic odors were directly found in the materials studied. The strongest odors identified were acetic, propanoic and butyric with vinegar and rancid odors and Octanal, nonanal and decanal with fat/soup odors, all of them found in PP and PE samples. Trimethylbenzenes with solvent and oily odors as well as terpenes with weakly woody odors were found in cardboard and paper materials. After migration, all compounds were below the European Legislation limits and maximum migration values recommended by Cramer. However propanoic, acetic and butyric acid as well as aldehydes compounds, phenol and 1-octanol were detected by sniffers, after migration assay, with high modified frequency (between 50 and 78%), what could change the organoleptic properties of packaged food.
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identification and quantification of odours from oxobiodegradable polyethylene oxidised under a free radical flow by headspace solid phase microextraction followed by gas chromatography olfactometry mass spectrometry
Talanta, 2017Co-Authors: Magdalena Wrona, Paula Vera, Davinson Pezo, Cristina NerinAbstract:Abstract Recently oxobiodegradable polyethylene gained popularity as food packaging material due to its potential to reduce polymer waste. However, this type of material can release after its oxidation off-odour compounds that affect the organoleptic properties of packaged food. Odour compounds released from both polyethylene and oxobiodegradable polyethylene before and after oxidation under a free radicals flow were investigated after 1 day, 2 days and 3 days of oxidation. The samples were analysed using headspace solid phase microextraction followed by gas chromatography-mass spectrometry and headspace solid phase microextraction coupled to gas chromatography-olfactometry-mass spectrometry. Sixty-two different odorous compounds were identified. 4-methylthio-2-butanone (fruit), nonanal (fat) and 3,6-nonadienal (fat) were present in different materials before oxidation. Multiple headspace-solid phase microextraction has been used to quantify all analytes. The most abundant compound was (Z)-3-hexenyl hexanoate with a concentration range between 1.5791±0.1387 µg/g and 4.8181±0.3123 µg/g. Compounds such as 2-dodecenal, 2-octenal, 2-pentanol, 3-nonenal, 3,6-nonadienal, ethyl 3-methylbutanoate, ethyl octenoate, hexanone, isopropyl hexanoate, Octanal were below their LOD evaluated using MS detector; however, they were detected by gas chromatography-olfactometry. The minimum LOD and LOQ were 0.011 µg/g and 0.036 µg/g, respectively.
Pengfei Yang - One of the best experts on this subject based on the ideXlab platform.
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coordinately unsaturated o2c ti5c o2c sites promote the reactivity of pt tio2 catalysts in the solvent free oxidation of n octanol
Catalysis Science & Technology, 2021Co-Authors: Pengfei Yang, Mark Douthwaite, Jiahao Pan, Lirong Zheng, Song Hong, David J Morgan, Mingyu Gao, Junting FengAbstract:A series of TiO2 anatase materials were synthesized with varying proportions of exposed (101) and (001) facets. Pt was subsequently impregnated onto these materials, which were then exposed to either an aerobic or reductive thermal treatment. The final catalysts were assessed for their performance in the aerobic, solvent free oxidation of octanol. Many kinds of characterization methods were employed to gain insight on how the exposed support facets influenced the catalysis. Thermal reduction of the catalysts led to a loss in the support surface structure, but in the contrary, after calcination, the defined facets remained, which was revealed by Raman and XRD. We further provide evidence that the coordinately unsaturated O2c–Ti5c–O2c sites present in the support promoted the dispersion of Pt after calcination in air, leading to the formation of low-coordinated and electron-deficient Pt clusters, based on high resolution- and spherical- aberration corrected transmission electron microscopy and X-ray absorption fine structure analysis. The calcined catalysts were far more active for both the oxidation of octanol and intermediate Octanal, thus resulting in a higher selectivity of octanoic acid. Catalyst performance closely correlated with the proportion of low-coordinated Pt species and the specific surface coordination structure of the support in the catalyst. Subsequent in situ Fourier transfer infrared experiments, conducted using alcohol and aldehydic probe molecules, confirmed that substrate adsorption was strongly influenced by the low-coordinated sites of both the Pt cluster and the exposed surface facets on the support.
Zaid Jumean - One of the best experts on this subject based on the ideXlab platform.
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identification of the larval aggregation pheromone of codling moth cydia pomonella
Journal of Chemical Ecology, 2005Co-Authors: Zaid Jumean, Regine Gries, Thomas R Unruh, Eloise Rowland, Gerhard GriesAbstract:Mature larvae of the codling moth, Cydia pomonella L. (Lepidoptera: Olethreutidae), exit the fruit and seek sites suitable for pupation. Spinning cocoons in such sites, larvae produce a complex, cocoon-derived blend of volatiles recently shown to attract and/or arrest both conspecific larvae and the prepupal parasitoid Mastrus ridibundus Gravenhorst (Hymenoptera: Ichneumonidae). Here we report components of this blend that constitute the pheromone of fifth-instar C. pomonella larvae. Thirty-one two-choice olfactometer experiments showed that a blend of synthetic (E)-2-octenal, (E)-2-nonenal, sulcatone, and geranylacetone, in combination with either 3-carene and/or three saturated aldehydes (Octanal, nonanal, decanal), elicited behavioral responses from C. pomonella larvae. In on-tree experiments with corrugated cardboard bands as pupation sites for larvae affixed to tree trunks, and with laboratory-reared larvae released onto such trees, more larvae cocooned in those halves of cardboard bands baited with cocoon-spinning conspecific larvae, or with synthetic pheromone components, than in unbaited control halves of the bands. With the larval aggregation pheromone identified in this study, there might be an opportunity to manipulate C. pomonella larvae in commercial fruit or nut orchards.
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Mastrus ridibundus parasitoids eavesdrop on cocoon-spinning codling moth, Cydia pomonella, larvae
Naturwissenschaften, 2005Co-Authors: Zaid Jumean, Tom Unruh, Regine Gries, Gerhard GriesAbstract:Cocoon-spinning larvae of the codling moth, Cydia pomonella L. (Lepidoptera: Olethreutidae) employ a pheromone that attracts or arrests conspecifics seeking pupation sites. Such intraspecific communication signals are important cues for illicit receivers such as parasitoids to exploit. We tested the hypothesis that the prepupal C. pomonella parasitoid Mastrus ridibundus Gravenhorst (Hymenoptera: Ichneumonidae) exploits the larval aggregation pheromone to locate host prepupae. In laboratory olfactometer experiments, female M. ridibundus were attracted to 3-day-old cocoons containing C. pomonella larvae or prepupae. Older cocoons containing C. pomonella pupae, or larvae and prepupae excised from cocoons, were not attractive. In gas chromatographic-electroantennographic detection (GC-EAD) analyses of bioactive Porapak Q extract of cocoon-derived airborne semiochemicals, ten compounds elicited responses from female M. ridibundus antennae. Comparative GC-mass spectrometry of authentic standards and cocoon-volatiles determined that these compounds were 3-carene, myrcene, heptanal, Octanal, nonanal, decanal, ( E )-2-octenal, ( E )-2-nonenal, sulcatone, and geranylacetone. A synthetic 11-component blend consisting of these ten EAD-active compounds plus EAD-inactive (+)-limonene (the most abundant cocoon-derived volatile) was as effective as Porapak Q cocoon extract in attracting both female M. ridibundus and C. pomonella larvae seeking pupation sites. Only three components could be deleted from the 11-component blend without diminishing its attractiveness to M. ridibundus , which underlines the complexity of information received and processed during foraging for hosts. Mastrus ridibundus obviously “eavesdrop” on the pheromonal communication signals of C. pomonella larvae that reliably indicate host presence.
