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Nigel P. Preston - One of the best experts on this subject based on the ideXlab platform.

  • Food sources of the sergestid crustacean, Acetes sibogae, in shrimp ponds
    Aquaculture, 2006
    Co-Authors: Frank Coman, Rod M. Connolly, Stuart E. Bunn, Nigel P. Preston
    Abstract:

    Abstract A combination of stable isotope measurements and gut contents analysis was used to determine the major food sources of the sergestid crustacean Acetes sibogae , in commercial shrimp ponds at two farms in southeast Queensland, Australia. Slight differences were observed between farms but overall the results were consistent. Although gut contents analysis gave a good indication of the range and temporal occurrence of food items consumed by Acetes , it was difficult to ascertain the contribution each item made to the diet. This was mainly due to the large proportion of unidentifiable material in the guts. All specimens examined contained unidentifiable material and about half the Acetes from both farms contained nothing identifiable. This unidentifiable material may be the result of processing by the Acetes gastric mill or the consumption of detritus, sediment or processed material from shrimp pellets. Only resilient items such as crustacean remains, diatoms and tinntinnids were commonly identified from the guts, and although present over the majority of the sampling period, FOCs were never greater than 25%. Stable isotope signals were measured for Acetes and likely food sources including pelleted shrimp feed, zooplankton and macroalgae. The pattern of changes in isotopic signals of Acetes across the season showed that zooplankton was a primary food source. Changes in the signals of zooplankton were reflected by changes in Acetes , but the changes in Acetes signal were less pronounced. At both farms, Acetes were more enriched in 13 C and 15 N (− 15‰ to − 20‰ and 12‰ to 13.8‰) than the zooplankton (− 18.9‰ to − 23.7‰ and 5‰ to 13.1‰), during the whole season. The absolute difference between the δ 13 C values of Acetes and zooplankton were more consistent than for δ 15 N, but both were greater than might be expected based on fractionation over a single trophic level. Furthermore, laboratory feeding trials showed that fractionation could not explain the greater than expected enrichment of the Acetes signal compared to that measured for zooplankton in the ponds. This, together with evidence from gut content analysis, showed that a food source other than zooplankton must also be important to Acetes . Macroalgae are the most likely additional source, although some minor contribution of pellets or microalgae cannot be ruled out entirely. There was no evidence from either gut contents or stable isotope signatures of dramatic dietary changes for Acetes either through a season or as they grew. It would appear unlikely that Acetes would have a great effect on shrimp production in ponds unless they were extremely abundant early in the season when the postlarvae are also feeding on zooplankton.

  • Food sources of the sergestid crustacean, Acetes sibogae, in shrimp ponds
    Aquaculture, 2006
    Co-Authors: Frank E. Coman, Rod M. Connolly, Stuart E. Bunn, Nigel P. Preston
    Abstract:

    A combination of stable isotope measurements and gut contents analysis was used to determine the major food sources of the sergestid crustacean Acetes sibogae, in commercial shrimp ponds at two farms in southeast Queensland, Australia. Slight differences were observed between farms but overall the results were consistent. Although gut contents analysis gave a good indication of the range and temporal occurrence of food items consumed by Acetes, it was difficult to ascertain the contribution each item made to the diet. This was mainly due to the large proportion of unidentifiable material in the guts. All specimens examined contained unidentifiable material and about half the Acetes from both farms contained nothing identifiable. This unidentifiable material may be the result of processing by the Acetes gastric mill or the consumption of detritus, sediment or processed material from shrimp pellets. Only resilient items such as crustacean remains, diatoms and tinntinnids were commonly identified from the guts, and although present over the majority of the sampling period, FOCs were never greater than 25%. Stable isotope signals were measured for Acetes and likely food sources including pelleted shrimp feed, zooplankton and macroalgae. The pattern of changes in isotopic signals of Acetes across the season showed that zooplankton was a primary food source. Changes in the signals of zooplankton were reflected by changes in Acetes, but the changes in Acetes signal were less pronounced. At both farms, Acetes were more enriched in 13C and 15N (- 15頴o - 20頡nd 12頴o 13.8驠than the zooplankton (- 18.9頴o - 23.7頡nd 5頴o 13.1马 during the whole season. The absolute difference between the d13C values of Acetes and zooplankton were more consistent than for d15N, but both were greater than might be expected based on fractionation over a single trophic level. Furthermore, laboratory feeding trials showed that fractionation could not explain the greater than expected enrichment of the Acetes signal compared to that measured for zooplankton in the ponds. This, together with evidence from gut content analysis, showed that a food source other than zooplankton must also be important to Acetes. Macroalgae are the most likely additional source, although some minor contribution of pellets or microalgae cannot be ruled out entirely. There was no evidence from either gut contents or stable isotope signatures of dramatic dietary changes for Acetes either through a season or as they grew. It would appear unlikely that Acetes would have a great effect on shrimp production in ponds unless they were extremely abundant early in the season when the postlarvae are also feeding on zooplankton.Griffith Sciences, Griffith School of EnvironmentNo Full Tex

Rod M. Connolly - One of the best experts on this subject based on the ideXlab platform.

  • Food sources of the sergestid crustacean, Acetes sibogae, in shrimp ponds
    Aquaculture, 2006
    Co-Authors: Frank Coman, Rod M. Connolly, Stuart E. Bunn, Nigel P. Preston
    Abstract:

    Abstract A combination of stable isotope measurements and gut contents analysis was used to determine the major food sources of the sergestid crustacean Acetes sibogae , in commercial shrimp ponds at two farms in southeast Queensland, Australia. Slight differences were observed between farms but overall the results were consistent. Although gut contents analysis gave a good indication of the range and temporal occurrence of food items consumed by Acetes , it was difficult to ascertain the contribution each item made to the diet. This was mainly due to the large proportion of unidentifiable material in the guts. All specimens examined contained unidentifiable material and about half the Acetes from both farms contained nothing identifiable. This unidentifiable material may be the result of processing by the Acetes gastric mill or the consumption of detritus, sediment or processed material from shrimp pellets. Only resilient items such as crustacean remains, diatoms and tinntinnids were commonly identified from the guts, and although present over the majority of the sampling period, FOCs were never greater than 25%. Stable isotope signals were measured for Acetes and likely food sources including pelleted shrimp feed, zooplankton and macroalgae. The pattern of changes in isotopic signals of Acetes across the season showed that zooplankton was a primary food source. Changes in the signals of zooplankton were reflected by changes in Acetes , but the changes in Acetes signal were less pronounced. At both farms, Acetes were more enriched in 13 C and 15 N (− 15‰ to − 20‰ and 12‰ to 13.8‰) than the zooplankton (− 18.9‰ to − 23.7‰ and 5‰ to 13.1‰), during the whole season. The absolute difference between the δ 13 C values of Acetes and zooplankton were more consistent than for δ 15 N, but both were greater than might be expected based on fractionation over a single trophic level. Furthermore, laboratory feeding trials showed that fractionation could not explain the greater than expected enrichment of the Acetes signal compared to that measured for zooplankton in the ponds. This, together with evidence from gut content analysis, showed that a food source other than zooplankton must also be important to Acetes . Macroalgae are the most likely additional source, although some minor contribution of pellets or microalgae cannot be ruled out entirely. There was no evidence from either gut contents or stable isotope signatures of dramatic dietary changes for Acetes either through a season or as they grew. It would appear unlikely that Acetes would have a great effect on shrimp production in ponds unless they were extremely abundant early in the season when the postlarvae are also feeding on zooplankton.

  • Food sources of the sergestid crustacean, Acetes sibogae, in shrimp ponds
    Aquaculture, 2006
    Co-Authors: Frank E. Coman, Rod M. Connolly, Stuart E. Bunn, Nigel P. Preston
    Abstract:

    A combination of stable isotope measurements and gut contents analysis was used to determine the major food sources of the sergestid crustacean Acetes sibogae, in commercial shrimp ponds at two farms in southeast Queensland, Australia. Slight differences were observed between farms but overall the results were consistent. Although gut contents analysis gave a good indication of the range and temporal occurrence of food items consumed by Acetes, it was difficult to ascertain the contribution each item made to the diet. This was mainly due to the large proportion of unidentifiable material in the guts. All specimens examined contained unidentifiable material and about half the Acetes from both farms contained nothing identifiable. This unidentifiable material may be the result of processing by the Acetes gastric mill or the consumption of detritus, sediment or processed material from shrimp pellets. Only resilient items such as crustacean remains, diatoms and tinntinnids were commonly identified from the guts, and although present over the majority of the sampling period, FOCs were never greater than 25%. Stable isotope signals were measured for Acetes and likely food sources including pelleted shrimp feed, zooplankton and macroalgae. The pattern of changes in isotopic signals of Acetes across the season showed that zooplankton was a primary food source. Changes in the signals of zooplankton were reflected by changes in Acetes, but the changes in Acetes signal were less pronounced. At both farms, Acetes were more enriched in 13C and 15N (- 15頴o - 20頡nd 12頴o 13.8驠than the zooplankton (- 18.9頴o - 23.7頡nd 5頴o 13.1马 during the whole season. The absolute difference between the d13C values of Acetes and zooplankton were more consistent than for d15N, but both were greater than might be expected based on fractionation over a single trophic level. Furthermore, laboratory feeding trials showed that fractionation could not explain the greater than expected enrichment of the Acetes signal compared to that measured for zooplankton in the ponds. This, together with evidence from gut content analysis, showed that a food source other than zooplankton must also be important to Acetes. Macroalgae are the most likely additional source, although some minor contribution of pellets or microalgae cannot be ruled out entirely. There was no evidence from either gut contents or stable isotope signatures of dramatic dietary changes for Acetes either through a season or as they grew. It would appear unlikely that Acetes would have a great effect on shrimp production in ponds unless they were extremely abundant early in the season when the postlarvae are also feeding on zooplankton.Griffith Sciences, Griffith School of EnvironmentNo Full Tex

Stuart E. Bunn - One of the best experts on this subject based on the ideXlab platform.

  • Food sources of the sergestid crustacean, Acetes sibogae, in shrimp ponds
    Aquaculture, 2006
    Co-Authors: Frank Coman, Rod M. Connolly, Stuart E. Bunn, Nigel P. Preston
    Abstract:

    Abstract A combination of stable isotope measurements and gut contents analysis was used to determine the major food sources of the sergestid crustacean Acetes sibogae , in commercial shrimp ponds at two farms in southeast Queensland, Australia. Slight differences were observed between farms but overall the results were consistent. Although gut contents analysis gave a good indication of the range and temporal occurrence of food items consumed by Acetes , it was difficult to ascertain the contribution each item made to the diet. This was mainly due to the large proportion of unidentifiable material in the guts. All specimens examined contained unidentifiable material and about half the Acetes from both farms contained nothing identifiable. This unidentifiable material may be the result of processing by the Acetes gastric mill or the consumption of detritus, sediment or processed material from shrimp pellets. Only resilient items such as crustacean remains, diatoms and tinntinnids were commonly identified from the guts, and although present over the majority of the sampling period, FOCs were never greater than 25%. Stable isotope signals were measured for Acetes and likely food sources including pelleted shrimp feed, zooplankton and macroalgae. The pattern of changes in isotopic signals of Acetes across the season showed that zooplankton was a primary food source. Changes in the signals of zooplankton were reflected by changes in Acetes , but the changes in Acetes signal were less pronounced. At both farms, Acetes were more enriched in 13 C and 15 N (− 15‰ to − 20‰ and 12‰ to 13.8‰) than the zooplankton (− 18.9‰ to − 23.7‰ and 5‰ to 13.1‰), during the whole season. The absolute difference between the δ 13 C values of Acetes and zooplankton were more consistent than for δ 15 N, but both were greater than might be expected based on fractionation over a single trophic level. Furthermore, laboratory feeding trials showed that fractionation could not explain the greater than expected enrichment of the Acetes signal compared to that measured for zooplankton in the ponds. This, together with evidence from gut content analysis, showed that a food source other than zooplankton must also be important to Acetes . Macroalgae are the most likely additional source, although some minor contribution of pellets or microalgae cannot be ruled out entirely. There was no evidence from either gut contents or stable isotope signatures of dramatic dietary changes for Acetes either through a season or as they grew. It would appear unlikely that Acetes would have a great effect on shrimp production in ponds unless they were extremely abundant early in the season when the postlarvae are also feeding on zooplankton.

  • Food sources of the sergestid crustacean, Acetes sibogae, in shrimp ponds
    Aquaculture, 2006
    Co-Authors: Frank E. Coman, Rod M. Connolly, Stuart E. Bunn, Nigel P. Preston
    Abstract:

    A combination of stable isotope measurements and gut contents analysis was used to determine the major food sources of the sergestid crustacean Acetes sibogae, in commercial shrimp ponds at two farms in southeast Queensland, Australia. Slight differences were observed between farms but overall the results were consistent. Although gut contents analysis gave a good indication of the range and temporal occurrence of food items consumed by Acetes, it was difficult to ascertain the contribution each item made to the diet. This was mainly due to the large proportion of unidentifiable material in the guts. All specimens examined contained unidentifiable material and about half the Acetes from both farms contained nothing identifiable. This unidentifiable material may be the result of processing by the Acetes gastric mill or the consumption of detritus, sediment or processed material from shrimp pellets. Only resilient items such as crustacean remains, diatoms and tinntinnids were commonly identified from the guts, and although present over the majority of the sampling period, FOCs were never greater than 25%. Stable isotope signals were measured for Acetes and likely food sources including pelleted shrimp feed, zooplankton and macroalgae. The pattern of changes in isotopic signals of Acetes across the season showed that zooplankton was a primary food source. Changes in the signals of zooplankton were reflected by changes in Acetes, but the changes in Acetes signal were less pronounced. At both farms, Acetes were more enriched in 13C and 15N (- 15頴o - 20頡nd 12頴o 13.8驠than the zooplankton (- 18.9頴o - 23.7頡nd 5頴o 13.1马 during the whole season. The absolute difference between the d13C values of Acetes and zooplankton were more consistent than for d15N, but both were greater than might be expected based on fractionation over a single trophic level. Furthermore, laboratory feeding trials showed that fractionation could not explain the greater than expected enrichment of the Acetes signal compared to that measured for zooplankton in the ponds. This, together with evidence from gut content analysis, showed that a food source other than zooplankton must also be important to Acetes. Macroalgae are the most likely additional source, although some minor contribution of pellets or microalgae cannot be ruled out entirely. There was no evidence from either gut contents or stable isotope signatures of dramatic dietary changes for Acetes either through a season or as they grew. It would appear unlikely that Acetes would have a great effect on shrimp production in ponds unless they were extremely abundant early in the season when the postlarvae are also feeding on zooplankton.Griffith Sciences, Griffith School of EnvironmentNo Full Tex

Samuel W. Thomas - One of the best experts on this subject based on the ideXlab platform.

  • Acenes beyond organic electronics: sensing of singlet oxygen and stimuli-responsive materials.
    Organic & Biomolecular Chemistry, 2020
    Co-Authors: Valentina Brega, Yu Yan, Samuel W. Thomas
    Abstract:

    The spectroscopic, electronic, and geometrical properties of acenes have enabled their broad applicability in organic optoelectronics. Beyond these physical characteristics of acenes, acenes also offer characteristic and predictable reaction chemistry, especially their behavior as dienes in cycloaddition reactions. Although these cycloaddition reactions, especially those with singlet oxygen (1O2) as the dienophile, are detrimental for organic electronics, this reactivity has led to several different applications such as sensing of 1O2, the release of cytotoxic reactive oxygen species (ROS), and stimuli-responsive materials for drug delivery. The rational design of acenes in these chemically-responsive applications beyond organic optoelectronics requires an understanding of how chemical structure influences both the physical properties, such as quantum yield of emission, as well as the reactivity of acenes and their cycloadducts. Therefore, the objective of this review is to summarize how cycloaddition reactions of acenes have expanded their applications in different areas of materials chemistry, and in doing so inspire and inform the rational design of acene-based materials with applications beyond organic electronics.

  • Spectroscopy and Reactivity of Dialkoxy Acenes
    Chemistry – A European Journal, 2019
    Co-Authors: Valentina Brega, Sare Nur Kanari, Connor T. Doherty, Dante Che, Seth A. Sharber, Samuel W. Thomas
    Abstract:

    Photochemical oxidation of acenes can benefit or impede their function, depending on the application. Although acenes with alkoxy substituents on reactive sites are important for applications as diverse as drug delivery and organic optoelectronics, the influence of chemical structure on their photochemical oxidation remains unknown. This paper therefore describes the synthesis, spectroscopic properties, and reactivity with singlet oxygen (1 O2 ) of a series of dialkoxyacenes that vary in the number and types of fused rings in the (hetero)acene cores. Reductive alkylation of quinone precursors yielded target dialkoxyacenes with fused backbones ranging from benzodithiophene to tetracenothiophene. Trends of their experimental spectroscopic characteristics were consistent with time-dependent density functional theory (TD-DFT) calculations. NMR studies show that photochemically generated 1 O2 oxidizes all but one of these acenes to the corresponding endoperoxides in organic solvent. The rates of these oxidations correlate with the number and types of fused arenes, with longer dialkoxyacenes generally oxidizing faster than shorter derivatives. Finally, irradiation of these acenes in acidic, oxidizing environments cleaves the ether bonds. This work impacts those working in organic optoelectronics, as well as those interested in harnessing photogenerated reactive oxygen species in functional materials.

  • Electronic effects of ring fusion and alkyne substitution on acene properties and reactivity.
    The Journal of Organic Chemistry, 2014
    Co-Authors: Jingjing Zhang, Zachary C. Smith, Samuel W. Thomas
    Abstract:

    This paper describes the synthesis and systematic study of substituted acenes that have differences in conjugation both along their long axes (by the number of fused benzene or thiophene rings) and along their short axes (by the number of arylethynyl substituents). These acenes include what we believe to be the first reported examples of five new subclasses of substituted acenes. Systematic analyses of data obtained using absorbance and fluorescence spectroscopies, cyclic voltammetry, and DFT calculations reveal clear correlations between these common structural perturbations to acene structure and the key parameters, such as HOMO–LUMO gap, frontier molecular orbital energies, and reactivity with singlet oxygen.

Chunyan Chi - One of the best experts on this subject based on the ideXlab platform.

  • Photochemistry of various acene based molecules
    Journal of Photochemistry and Photobiology C: Photochemistry Reviews, 2019
    Co-Authors: Shaoqiang Dong, Albert Ong, Chunyan Chi
    Abstract:

    Abstract Photochemistry based on acenes and their derivatives is one of the emerging research areas in the field of polycyclic aromatic hydrocarbons (PAHs). However, due to the increased reactivity of larger acenes towards light and singlet oxygen, it is difficult to precisely control their photochemical reactions. Therefore, the unexpected reactivity of acene-based molecules brings about two challenging topics: how to design stable acenes and how to utilize the photochemistry to design new acene-based functional materials. In this review, we first focus on the mechanism of photochemistry of acenes to theoretically understand how these reactions could have happened. Next, we will give a summary on both acene-based photocyclization and photooxidation reactions.

  • Different Strategies for the Stabilization of Acenes and Acene Analogues
    The Chemical Record, 2016
    Co-Authors: Xueliang Shi, Chunyan Chi
    Abstract:

    Acenes, a type of polycyclic aromatic hydrocarbon containing linearly fused benzene rings, have received much attention from organic chemists, physical chemists, and materials scientists, due to their intriguing properties and potential applications in organic electronics. Without doubt, acene chemistry has been one of the hottest topics among the π-conjugated systems. However, poor stability of acenes is the prominent issue that limits their applications. In this personal account, we summarize different strategies developed in our group to construct and stabilize acenes and acene analogues. In addition, the unique properties and applications of some molecules will be discussed.

  • Recent Highlights and Perspectives on Acene Based Molecules and Materials
    Chemistry of Materials, 2014
    Co-Authors: Chunyan Chi
    Abstract:

    Acenes represent a series of molecules with intriguing physical and chemical properties for applications in organic electronics. Nevertheless, the stability and solubility issues associated with longer acenes are two major obstacles for their applications. In this Perspective, we summarize the major design principles for stabilizing acenes. A variety of stable acene based derivatives are included for discussion. Finally, we highlight some research areas where breakthroughs will be critical for the further development of acene based molecules and materials.