Evaluating the influence of wetland vegetation on chemical residence time in Mississippi Delta drainage ditches   总被引：2，自引：0，他引：2  

R. Kröger  M.T. Moore  R.F. Cullum  S. Testa III  C.M. Cooper 《Agricultural Water Management》2009,96(7):1175-1179

The presence of emergent vegetation within channelized aquatic environments has the capacity to provide a number of biological functions as well as alter the hydrology of the system. Vegetation within the channel exerts roughness, drag and friction on flowing water, reducing flow rates, increasing water depths and increasing hydraulic retention time. By increasing the hydraulic retention time, chemical residence time (CRT) is increased, thus improving the potential of pollutant mitigation. The study compared two geomorphologically similar drainage ditches, one vegetated and one non-vegetated to evaluate the effect obligate, in-stream wetland vegetation had on CRT. A fluoride (F⁻) tracer was amended to both ditches with nutrients and sediments to simulate stormwater runoff event. The measured CRT of the vegetated drainage ditch was at least twice that of the non-vegetated ditch. These results suggest that with the presence of vegetation increasing CRT, chemical removal rates will improve, and as a result increase the possibility of microbial transformation, adsorption, and macrophyte assimilation. By dredging or clear-scraping ditches and removing the vegetative component, farmers and managers alike will increase water flows, decrease CRT and potentially increase pollutant loads into aquatic receiving systems.  相似文献   

External and digestive system morphology of the Tamandua tetradactyla     

Milena de Oliveira Firmino  Helder Camilo da Silva Pereira  Lucas Rannier Ribeiro Antonino Carvalho  Ricardo Romão Guerra 《Anatomia, histologia, embryologia》2020,49(1):97-104

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Identification of aminoethylcysteine ketimine decarboxylated dimer, a natural antioxidant, in dietary vegetables     

Macone A  Nardini M  Antonucci A  Maggio A  Matarese RM 《Journal of agricultural and food chemistry》2002,50(7):2169-2172

Aminoethylcysteine ketimine decarboxylated dimer (simply named dimer) is a natural sulfur-containing tricyclic compound detected, until now, in human urine, bovine cerebellum, and human plasma. Recently, the antioxidant properties of this compound have been demonstrated. In this investigation, the presence of aminoethylcysteine ketimine decarboxylated dimer was identified in garlic, spinach, tomato, asparagus, aubergine, onion, pepper, and courgette. Identification of this compound in dietary vegetables was performed using gas chromatography, high-performance liquid chromatography, and gas chromatography-mass spectrometry. Results from GC analysis range in the order of 10(-4) micromol of dimer/g for all the tested vegetables. These results and the lack of a demonstrated biosynthetic pathway in humans might account for a dietary supply of this molecule.  相似文献   

Mathematical modeling for evaluating gain of logging companies in the timber market     

Francesco CARBONE  Antonino SCARELLI  Zoltan VARGA 《中国林学(英文版)》2013,15(1):41-48

We propose a game-theoretic model for a first-price sealed-bid auction (FPSB auction) of standing timber. A FPSB auction means that bidders simultaneously submit sealed bids so that no bidder knows the bid of any other participant. The highest bidder pays the submitted price. The mathematical model has been elaborated considering only two bidders. Each bidder is supposed to know only the probability distribution of the bid of the other bidder. Using appropriate distributions, the adversity and propensity of a bidder to risk can be described. From the view point of a bidder, the conservative solution is calculated for both types of the other bidder. If a standing timber belongs to a public owner, the market has to follow a public evidence procedure, including public auctions. The function obtained is illustrated with a numerical example of a typical standing timber auction from a forest located in central Italy. Considering average costs and prices of the local chestnut timber market, winning bids and expected gains are estimated. Their amounts are comparable with the currently average stumpage price registered in this market.  相似文献   

Anti-cariogenic effects of polyphenols from plant stimulant beverages (cocoa,coffee, tea)     

Gianmaria F. Ferrazzano  Ivana Amato  Aniello Ingenito  Antonino De Natale  Antonino Pollio 《Fitoterapia》2009

Polyphenols occurring in cocoa, coffee and tea can have a role in the prevention of cariogenic processes, due to their antibacterial action. Cocoa polyphenol pentamers significantly reduce biofilm formation and acid production by Streptococcus mutans and S. sanguinis. In the same way, trigonelline, caffeine and chlorogenic acid occurring in green and roasted coffee interfere with S. mutans adsorption to saliva-coated hydroxyapatite beads. Studies carried out on green, oolong and black tea indicate that tea polyphenols exert an anti-caries effect via an anti-microbial mode-of-action, and galloyl esters of (−)-epicatechin, (−)-epigallocatechin and (−)-gallocatechin show increasing antibacterial activities. The anti-cariogenic effects against α-haemolytic streptococci showed by polyphenols from cocoa, coffee, and tea suggest further studies to a possible application of these beverages in the prevention of pathogenesis of dental caries.  相似文献   

CT assessment in canine meningoencephalomyelitis     

Drago V  Fatone G  Testa A  Reale S  Paciello O  Meomartino L 《Veterinary research communications》2008,32(Z1):S279-S281

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A possible relativistic jetted outburst from a massive black hole fed by a tidally disrupted star     

Bloom JS  Giannios D  Metzger BD  Cenko SB  Perley DA  Butler NR  Tanvir NR  Levan AJ  O'Brien PT  Strubbe LE  De Colle F  Ramirez-Ruiz E  Lee WH  Nayakshin S  Quataert E  King AR  Cucchiara A  Guillochon J  Bower GC  Fruchter AS  Morgan AN  van der Horst AJ 《Science (New York, N.Y.)》2011,333(6039):203-206

Gas accretion onto some massive black holes (MBHs) at the centers of galaxies actively powers luminous emission, but most MBHs are considered dormant. Occasionally, a star passing too near an MBH is torn apart by gravitational forces, leading to a bright tidal disruption flare (TDF). Although the high-energy transient Sw 1644+57 initially displayed none of the theoretically anticipated (nor previously observed) TDF characteristics, we show that observations suggest a sudden accretion event onto a central MBH of mass about 10(6) to 10(7) solar masses. There is evidence for a mildly relativistic outflow, jet collimation, and a spectrum characterized by synchrotron and inverse Compton processes; this leads to a natural analogy of Sw 1644+57 to a temporary smaller-scale blazar.  相似文献   

The Ethics of Deriving Gametes from ES Cells     

Lippman A  Newman SA  Testa G  Harris J 《Science (New York, N.Y.)》2005,307(5709):515-7; author reply 515-7

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Lipid oxidation and amylopectin molecular weight changes occurring during storage of extruded starch samples     

Sarah E. Bowen  David A. Gray  Chrystelle Giraud  Mahsa Majzoobi  Claudia E. Millan Testa  Luis A. Bello Prez  Sandra E. Hill 《Journal of Cereal Science》2006,43(3):275-283

Using thermomechanical extrusion, waxy maize starch and 4% (w/w) lipid were formed into strips. The lipids used were free fatty acids (mostly linoleic) and antioxidant stripped sunflower oil (either previously oxidised or fresh, with and without copper ions). By altering their water content it was possible to store, at the same temperature, sample strips in the glassy and rubbery states. Lipid oxidation was monitored by determining hexanal in the headspace above all stored samples. The molecular weights of the amylopectin in the samples of extruded products (dissolved in dimethylsulfoxide, precipitated and redissolved using a pressure cell) were determined by asymmetric flow-field-flow fractionation, analytical ultracentrifugation and light scattering. The initial rate of hexanal generation was higher in samples stored in the glassy state compared with those in the rubbery state. Waxy maize and extruded samples, at the start of the storage period and after 42 days, were used to establish the molecular weight of the amylopectin. A significant fall (a decrease of 40%) in molecular weight was found on storage of samples containing sunflower oil and copper ions and those containing free fatty acids, irrespective of the method used for molecular weight determination.  相似文献   

Lethal and sublethal responses of <Emphasis Type="Italic">Sitophilus zeamais</Emphasis> populations to essential oils     

Alice Maria Nascimento de Araújo  Lêda Rita D’Antonino. Faroni  José Vargas de Oliveira  Daniela Maria do Amaral Ferraz Navarro  Douglas Rafael e Silva Barbosa  Mariana Oliveira Breda  Solange Maria de França 《Journal of pest science》2017,90(2):589-600

The present study aimed to assess the lethal and sublethal responses of five populations of S. zeamais to the essential oils of Ocimum basilicum and Piper hispidinervum, through toxicity, locomotor behavior (flight and walking activities) and physiological (respiration rate and body mass) evaluations. The populations of S. zeamais were obtained from Machado—MG, Paracatu—MG, Piracicaba—SP, Recife—PE and Tunápolis—SC. To estimate the LC₅₀ of each oil for each population, fumigation tests were performed. The population from Recife exhibited the lowest instantaneous rate of increase (ri) as well the lowest consumption of grain mass. However, Piracicaba was considered the susceptibility pattern, presenting the lowest LC₅₀ for both essential oils, no statistical difference was observed among populations or treatments in the flight activity bioassays. The essential oils effect on walking activity and respiration rates varied among populations. The population from Recife presented the highest walked distance and walk speed, with the lowest resting time and number of stops, as well as the lowest respiration rate and body mass. The present study highlights the importance of the study on population responses, as the five populations of S. zeamais exhibited different patterns of toxic and behavioral effects when subjected to the essential oils of P. hispidinervum and O. basilicum.  相似文献