WorldWideScience

Sample records for terpenes mechanistic view

  1. A mechanistic view of mitochondrial death decision pores

    Directory of Open Access Journals (Sweden)

    J.E. Belizário

    2007-08-01

    Full Text Available Mitochondria increase their outer and inner membrane permeability to solutes, protons and metabolites in response to a variety of extrinsic and intrinsic signaling events. The maintenance of cellular and intraorganelle ionic homeostasis, particularly for Ca2+, can determine cell survival or death. Mitochondrial death decision is centered on two processes: inner membrane permeabilization, such as that promoted by the mitochondrial permeability transition pore, formed across inner membranes when Ca2+ reaches a critical threshold, and mitochondrial outer membrane permeabilization, in which the pro-apoptotic proteins BID, BAX, and BAK play active roles. Membrane permeabilization leads to the release of apoptogenic proteins: cytochrome c, apoptosis-inducing factor, Smac/Diablo, HtrA2/Omi, and endonuclease G. Cytochrome c initiates the proteolytic activation of caspases, which in turn cleave hundreds of proteins to produce the morphological and biochemical changes of apoptosis. Voltage-dependent anion channel, cyclophilin D, adenine nucleotide translocase, and the pro-apoptotic proteins BID, BAX, and BAK may be part of the molecular composition of membrane pores leading to mitochondrial permeabilization, but this remains a central question to be resolved. Other transporting pores and channels, including the ceramide channel, the mitochondrial apoptosis-induced channel, as well as a non-specific outer membrane rupture may also be potential release pathways for these apoptogenic factors. In this review, we discuss the mechanistic models by which reactive oxygen species and caspases, via structural and conformational changes of membrane lipids and proteins, promote conditions for inner/outer membrane permeabilization, which may be followed by either opening of pores or a rupture of the outer mitochondrial membrane.

  2. [Regulation of terpene metabolism

    Energy Technology Data Exchange (ETDEWEB)

    Croteau, R.

    1989-11-09

    Terpenoid oils, resins, and waxes from plants are important renewable resources. The objective of this project is to understand the regulation of terpenoid metabolism using the monoterpenes (C[sub 10]) as a model. The pathways of monoterpene biosynthesis and catabolism have been established, and the relevant enzymes characterized. Developmental studies relating enzyme levels to terpene accumulation within the oil gland sites of synthesis, and work with bioregulators, indicate that monoterpene production is controlled by terpene cyclases, the enzymes catalyzing the first step of the monoterpene pathway. As the leaf oil glands mature, cyclase levels decline and monoterpene biosynthesis ceases. Yield then decreases as the monoterpenes undergo catabolism by a process involving conversion to a glycoside and transport from the leaf glands to the root. At this site, the terpenoid is oxidatively degraded to acetate that is recycled into other lipid metabolites. During the transition from terpene biosynthesis to catabolism, the oil glands undergo dramatic ultrastructural modification. Degradation of the producing cells results in mixing of previously compartmentized monoterpenes with the catabolic enzymes, ultimately leading to yield decline. This regulatory model is being applied to the formation of other terpenoid classes (C[sub 15] C[sub 20], C[sub 30], C[sub 40]) within the oil glands. Preliminary investigations on the formation of sesquiterpenes (C[sub 15]) suggest that the corresponding cyclases may play a lesser role in determining yield of these products, but that compartmentation effects are important. From these studies, a comprehensive scheme for the regulation of terpene metabolism is being constructed. Results from this project wail have important consequences for the yield and composition of terpenoid natural products that can be made available for industrial exploitation.

  3. [Regulation of terpene metabolism

    Energy Technology Data Exchange (ETDEWEB)

    Croteau, R.

    1992-01-01

    This report describes accomplishments over the past year on understanding of terpene synthesis in mint plants and sage. Specifically reported are the fractionation of 4-S-limonene synthetase, the enzyme responsible for the first committed step to monoterpene synthesis, along with isolation of the corresponding RNA and DNA cloning of its gene; the localization of the enzyme within the oil glands, regulation of transcription and translation of the synthetase, the pathway to camphor biosynthesis,a nd studies on the early stages and branch points of the isoprenoid pathway.

  4. Terpene synthases from Cannabis sativa.

    Directory of Open Access Journals (Sweden)

    Judith K Booth

    Full Text Available Cannabis (Cannabis sativa plants produce and accumulate a terpene-rich resin in glandular trichomes, which are abundant on the surface of the female inflorescence. Bouquets of different monoterpenes and sesquiterpenes are important components of cannabis resin as they define some of the unique organoleptic properties and may also influence medicinal qualities of different cannabis strains and varieties. Transcriptome analysis of trichomes of the cannabis hemp variety 'Finola' revealed sequences of all stages of terpene biosynthesis. Nine cannabis terpene synthases (CsTPS were identified in subfamilies TPS-a and TPS-b. Functional characterization identified mono- and sesqui-TPS, whose products collectively comprise most of the terpenes of 'Finola' resin, including major compounds such as β-myrcene, (E-β-ocimene, (--limonene, (+-α-pinene, β-caryophyllene, and α-humulene. Transcripts associated with terpene biosynthesis are highly expressed in trichomes compared to non-resin producing tissues. Knowledge of the CsTPS gene family may offer opportunities for selection and improvement of terpene profiles of interest in different cannabis strains and varieties.

  5. [Regulation of terpene metabolism

    Energy Technology Data Exchange (ETDEWEB)

    Croteau, R.

    1991-01-01

    During the last grant period, we have completed studies on the key pathways of monoterpene biosynthesis and catabolism in sage and peppermint, and have, by several lines of evidence, deciphered the rate-limiting step of each pathway. We have at least partially purified and characterized the relevant enzymes of each pathway. We have made a strong case, based on analytical, in vivo, and in vitro studies, that terpene accumulation depends upon the balance between biosynthesis and catabolism, and provided supporting evidence that these processes are developmentally-regulated and very closely associated with senescence of the oil glands. Oil gland ontogeny has been characterized at the ultrastructural level. We have exploited foliar-applied bioregulators to delay gland senescence, and have developed tissue explant and cell culture systems to study several elusive aspects of catabolism. We have isolated pure gland cell clusters and localized monoterpene biosynthesis and catabolism within these structures, and have used these preparations as starting materials for the purification to homogeneity of target regulatory'' enzymes. We have thus developed the necessary background knowledge, based on a firm understanding of enzymology, as well as the necessary experimental tools for studying the regulation of monoterpene metabolism at the molecular level. Furthermore, we are now in a position to extend our systematic approach to other terpenoid classes (C[sub 15]-C[sub 30]) produced by oil glands.

  6. The ecophysiology of seed persistence: a mechanistic view of the journey to germination or demise.

    Science.gov (United States)

    Long, Rowena L; Gorecki, Marta J; Renton, Michael; Scott, John K; Colville, Louise; Goggin, Danica E; Commander, Lucy E; Westcott, David A; Cherry, Hillary; Finch-Savage, William E

    2015-02-01

    Seed persistence is the survival of seeds in the environment once they have reached maturity. Seed persistence allows a species, population or genotype to survive long after the death of parent plants, thus distributing genetic diversity through time. The ability to predict seed persistence accurately is critical to inform long-term weed management and flora rehabilitation programs, as well as to allow a greater understanding of plant community dynamics. Indeed, each of the 420000 seed-bearing plant species has a unique set of seed characteristics that determine its propensity to develop a persistent soil seed bank. The duration of seed persistence varies among species and populations, and depends on the physical and physiological characteristics of seeds and how they are affected by the biotic and abiotic environment. An integrated understanding of the ecophysiological mechanisms of seed persistence is essential if we are to improve our ability to predict how long seeds can survive in soils, both now and under future climatic conditions. In this review we present an holistic overview of the seed, species, climate, soil, and other site factors that contribute mechanistically to seed persistence, incorporating physiological, biochemical and ecological perspectives. We focus on current knowledge of the seed and species traits that influence seed longevity under ex situ controlled storage conditions, and explore how this inherent longevity is moderated by changeable biotic and abiotic conditions in situ, both before and after seeds are dispersed. We argue that the persistence of a given seed population in any environment depends on its resistance to exiting the seed bank via germination or death, and on its exposure to environmental conditions that are conducive to those fates. By synthesising knowledge of how the environment affects seeds to determine when and how they leave the soil seed bank into a resistance-exposure model, we provide a new framework for

  7. 21 CFR 172.280 - Terpene resin.

    Science.gov (United States)

    2010-04-01

    ... CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Coatings, Films and Related Substances § 172.280 Terpene resin. The food additive terpene resin may be safely used...

  8. Methods for high yield production of terpenes

    Energy Technology Data Exchange (ETDEWEB)

    Kutchan, Toni; Higashi, Yasuhiro; Feng, Xiaohong

    2017-01-03

    Provided are enhanced high yield production systems for producing terpenes in plants via the expression of fusion proteins comprising various combinations of geranyl diphosphate synthase large and small subunits and limonene synthases. Also provided are engineered oilseed plants that accumulate monoterpene and sesquiterpene hydrocarbons in their seeds, as well as methods for producing such plants, providing a system for rapidly engineering oilseed crop production platforms for terpene-based biofuels.

  9. Differential sensing using proteins: exploiting the cross-reactivity of serum albumin to pattern individual terpenes and terpenes in perfume.

    Science.gov (United States)

    Adams, Michelle M; Anslyn, Eric V

    2009-12-02

    There has been a growing interest in the use of differential sensing for analyte classification. In an effort to mimic the mammalian senses of taste and smell, which utilize protein-based receptors, we have introduced serum albumins as nonselective receptors for recognition of small hydrophobic molecules. Herein, we employ a sensing ensemble consisting of serum albumins, a hydrophobic fluorescent indicator (PRODAN), and a hydrophobic additive (deoxycholate) to detect terpenes. With the aid of linear discriminant analysis, we successfully applied our system to differentiate five terpenes. We then extended our terpene analysis and utilized our sensing ensemble for terpene discrimination within the complex mixtures found in perfume.

  10. [Regulation of terpene metabolism.] Progress report

    International Nuclear Information System (INIS)

    Croteau, R.

    1984-01-01

    This research program represents a very broad-based approach to understanding the biochemistry of the monoterpene and sesquiterpene constituents of the essential oils. This program includes basic research on the pathways, enzymes and mechanisms of terpene biosynthesis and catabolism, on the physiology of essential oil production, and on the morphology and development of oil glands, as well as practical approaches to manipulating essential oil composition and yield. As a natural extension of research on monoterpene biosynthesis and catabolism in sage and peppermint we have explored some aspects of possible regulatory mechanisms. Tentative evidence has been obtained for developmental regulation of the levels of biosynthetic and catabolic enzymes. 10 refs., 8 figs

  11. Cyclopentanoid terpene biosynthesis in a phasmid insect and in catmint.

    Science.gov (United States)

    Meinwald, J; Happ, G M; Labows, J; Eisner, T

    1966-01-07

    The stick insect, Anisomorpha buprestoides, and the catmint, Nepeta cataria, produce closely related cyclopentanoid terpenes, anisomorphal and nepetalactone. Tracer experiments with isotopes indicate that anisomorphal is synthesized by the walking stick from normal terpene precursors (acetate or mevalonate). In the catmint plant, isolated leaf disks synthesized nepetalactone, utilizing the same precursors.

  12. Selected oxidized fragrance terpenes are common contact allergens

    DEFF Research Database (Denmark)

    Matura, Mihaly; Sköld, Maria; Börje, Anna

    2005-01-01

    Terpenes are widely used fragrance compounds in fine fragrances, but also in domestic and occupational products. Terpenes oxidize easily due to autoxidation on air exposure. Previous studies have shown that limonene, linalool and caryophyllene are not allergenic themselves but readily form...... allergenic products on air-exposure. This study aimed to determine the frequency and characteristics of allergic reactions to selected oxidized fragrance terpenes other than limonene. In total 1511 consecutive dermatitis patients in 6 European dermatology centres were patch tested with oxidized fragrance...... to oxidized caryophyllene whereas 1 patient reacted to oxidized myrcene. Of the patients reacting to the oxidized terpenes, 58% had fragrance-related contact allergy and/or a positive history for adverse reaction to fragrances. Autoxidation of fragrance terpenes contributes greatly to fragrance allergy, which...

  13. Terpenes removal from biogas; Terpenenverwijdering uit biogas

    Energy Technology Data Exchange (ETDEWEB)

    Schulze, P.; Holstein, J.; De Haan, HR.; Vlap, H. [DNV KEMA, Arnhem (Netherlands)

    2013-06-15

    Biogas may contain unwanted and harmful components, including aromatic hydrocarbons such as terpenes. These terpenes (organic oils) are mainly present in citrus peel and plant residues; that is why especially raw biogas from organic waste digestion plants contains high concentrations of terpenes. If terpenes end up in the gas grid (with the injected biomethane) there is a risk that plastics (PE pipes) lose their mechanical properties by absorbing liquids or extracting ethereal plasticizers. This can lead to embrittlement greatly lowering the reliability of the piping. In addition, soft components are als o affected (gaskets and rubber O-rings). Besides the impact on the integrity of the gas grid, terpenes also mask the odor of natural gas odorants such as THT. This impedes the detection of gas leaks which is a significant security risk. Furthermore, the presence of terpenes in biogas leads to fouling of equipment used for the drying of biomethane, as well as contamination of adsorption liquids and membranes used in the upgrading process. Currently, terpenes are removed by activated carbon filters. The tool life of such a filter can be relatively short if terpene concentrations are high in the biogas; this results in a significant increase of the operational costs, due to the replacement of the carbon. This study looked at alternative techniques for removing much of the terpenes from biogas in a simple, efficient and cheap way. In a workshop with stakeholders two techniques were chosen to be tested on laboratory scale in order to demonstrate the proof of principle. These techniques are photo-oxydation and a gas scrubbing. Of all investigated techniques for the removal of limonene the application of UV radiation seems to be the most promising option because of the simplicity of the process, the high efficiency (up to 94%), the comparable operational costs with activated carbon (6.7 to 9.5 euro/kg limonene removed, compared to 10 euro/kg limonene removed for activated

  14. Selected oxidized fragrance terpenes are common contact allergens.

    Science.gov (United States)

    Matura, Mihaly; Sköld, Maria; Börje, Anna; Andersen, Klaus E; Bruze, Magnus; Frosch, Peter; Goossens, An; Johansen, Jeanne D; Svedman, Cecilia; White, Ian R; Karlberg, Ann-Therese

    2005-06-01

    Terpenes are widely used fragrance compounds in fine fragrances, but also in domestic and occupational products. Terpenes oxidize easily due to autoxidation on air exposure. Previous studies have shown that limonene, linalool and caryophyllene are not allergenic themselves but readily form allergenic products on air-exposure. This study aimed to determine the frequency and characteristics of allergic reactions to selected oxidized fragrance terpenes other than limonene. In total 1511 consecutive dermatitis patients in 6 European dermatology centres were patch tested with oxidized fragrance terpenes and some oxidation fractions and compounds. Oxidized linalool and its hydroperoxide fraction were found to be common contact allergens. Of the patients tested, 1.3% showed a positive reaction to oxidized linalool and 1.1% to the hydroperoxide fraction. About 0.5% of the patients reacted to oxidized caryophyllene whereas 1 patient reacted to oxidized myrcene. Of the patients reacting to the oxidized terpenes, 58% had fragrance-related contact allergy and/or a positive history for adverse reaction to fragrances. Autoxidation of fragrance terpenes contributes greatly to fragrance allergy, which emphasizes the need of testing with compounds that patients are actually exposed to and not only with the ingredients originally applied in commercial formulations.

  15. Terpenic profile of different Rosmarinus officinalis extracts.

    Science.gov (United States)

    Olah, Neli-Kinga; Benedec, Daniela; Socaci, Sonia; Toma, Claudia Crina; Filip, Lorena; Morgovan, Claudiu; Hanganu, Daniela

    2017-07-01

    The Rosemary (Rosmarinus officinalis L.), a well-known medicinal and culinary herb, was studied to compare the terpenic profile of different extracts obtained from dry and fresh herb. There were studied the volatile oil extracted by hydro distillation from dry plant, the hydroalcoholic extracts obtained from fresh respectively dry plant and the glycerol macerate obtained from fresh plant, by GC-MS using headspace injection. The separated compounds were identified using a MS spectra library. The quantitative determination was performed by normalization respectively by calibration curve method for 1,8-cineole, alpha-pinene and D-limonene. The main separated compounds were alpha-pinene, 1,8-cineol, camphene, camphor, D-limonene and cymene. A significant difference was observed between the 4 samples volatile profiles. 1,8-cineole was found major component of the essential oil (VO-21.39%) and glycerol macerate (GM-35.60%), while and α-pinene was detected as the main constituent of the two tinctures (T-46.05%; MT-31.93%). The highest 1,8-cineol content, determined by calibration curve method, was found in the volatile oil, while the fresh plant hydroalcoholic extract was richer in α-pinene and D-limonene.

  16. Terpene and dextran renewable resources for the synthesis of amphiphilic biopolymers.

    Science.gov (United States)

    Alvès, Marie-Hélène; Sfeir, Huda; Tranchant, Jean-François; Gombart, Emilie; Sagorin, Gilles; Caillol, Sylvain; Billon, Laurent; Save, Maud

    2014-01-13

    The present work shows the synthesis of amphiphilic polymers based on the hydrophilic dextran and the hydrophobic terpenes as renewable resources. The first step concerns the synthesis of functional terpene molecules by thiol-ene addition chemistry involving amino or carboxylic acid thiols and dihydromyrcenol terpene. The terpene-modified polysaccharides were subsequently synthesized by coupling the functional terpenes with dextran. A reductive amination step produced terpene end-modified dextran with 94% of functionalization, while the esterification step produced three terpene-grafted dextrans with a number of terpene units per dextran of 1, 5, and 10. The amphiphilic renewable grafted polymers were tested as emulsifiers for the stabilization of liquid miniemulsion of terpene droplets dispersed in an aqueous phase. The average hydrodynamic diameter of the stable droplets was observed at about 330 nm.

  17. Progress in terpene synthesis strategies through engineering of Saccharomyces cerevisiae.

    Science.gov (United States)

    Paramasivan, Kalaivani; Mutturi, Sarma

    2017-12-01

    Terpenes are natural products with a remarkable diversity in their chemical structures and they hold a significant market share commercially owing to their distinct applications. These potential molecules are usually derived from terrestrial plants, marine and microbial sources. In vitro production of terpenes using plant tissue culture and plant metabolic engineering, although receiving some success, the complexity in downstream processing because of the interference of phenolics and product commercialization due to regulations that are significant concerns. Industrial workhorses' viz., Escherichia coli and Saccharomyces cerevisiae have become microorganisms to produce non-native terpenes in order to address critical issues such as demand-supply imbalance, sustainability and commercial viability. S. cerevisiae enjoys several advantages for synthesizing non-native terpenes with the most significant being the compatibility for expressing cytochrome P450 enzymes from plant origin. Moreover, achievement of high titers such as 40 g/l of amorphadiene, a sesquiterpene, boosts commercial interest and encourages the researchers to envisage both molecular and process strategies for developing yeast cell factories to produce these compounds. This review contains a brief consideration of existing strategies to engineer S. cerevisiae toward the synthesis of terpene molecules. Some of the common targets for synthesis of terpenes in S. cerevisiae are as follows: overexpression of tHMG1, ERG20, upc2-1 in case of all classes of terpenes; repression of ERG9 by replacement of the native promoter with a repressive methionine promoter in case of mono-, di- and sesquiterpenes; overexpression of BTS1 in case of di- and tetraterpenes. Site-directed mutagenesis such as Upc2p (G888A) in case of all classes of terpenes, ERG20p (K197G) in case of monoterpenes, HMG2p (K6R) in case of mono-, di- and sesquiterpenes could be some generic targets. Efforts are made to consolidate various studies

  18. Functional Genomics Reveals That a Compact Terpene Synthase Gene Family Can Account for Terpene Volatile Production in Apple1[W

    Science.gov (United States)

    Nieuwenhuizen, Niels J.; Green, Sol A.; Chen, Xiuyin; Bailleul, Estelle J.D.; Matich, Adam J.; Wang, Mindy Y.; Atkinson, Ross G.

    2013-01-01

    Terpenes are specialized plant metabolites that act as attractants to pollinators and as defensive compounds against pathogens and herbivores, but they also play an important role in determining the quality of horticultural food products. We show that the genome of cultivated apple (Malus domestica) contains 55 putative terpene synthase (TPS) genes, of which only 10 are predicted to be functional. This low number of predicted functional TPS genes compared with other plant species was supported by the identification of only eight potentially functional TPS enzymes in apple ‘Royal Gala’ expressed sequence tag databases, including the previously characterized apple (E,E)-α-farnesene synthase. In planta functional characterization of these TPS enzymes showed that they could account for the majority of terpene volatiles produced in cv Royal Gala, including the sesquiterpenes germacrene-D and (E)-β-caryophyllene, the monoterpenes linalool and α-pinene, and the homoterpene (E)-4,8-dimethyl-1,3,7-nonatriene. Relative expression analysis of the TPS genes indicated that floral and vegetative tissues were the primary sites of terpene production in cv Royal Gala. However, production of cv Royal Gala floral-specific terpenes and TPS genes was observed in the fruit of some heritage apple cultivars. Our results suggest that the apple TPS gene family has been shaped by a combination of ancestral and more recent genome-wide duplication events. The relatively small number of functional enzymes suggests that the remaining terpenes produced in floral and vegetative and fruit tissues are maintained under a positive selective pressure, while the small number of terpenes found in the fruit of modern cultivars may be related to commercial breeding strategies. PMID:23256150

  19. Production of terpenes in the culture of Chlorophyceae and Rhodophyta

    Science.gov (United States)

    Abe, M.; Hashimoto, S.

    2014-12-01

    Terpenes show high reactivity in the troposphere, contributing to organic aerosol reactions with OH radicals. One of the main sources of terpenes in the atmosphere is terrestrial plants. It has been recently reported that marine phytoplankton also produce monoterpenes (Yassaa et al: 2008). Because aerosol production of natural origin affects the cloud cover over the open ocean, it is important to investigate the origin of aerosol generation in the open ocean. In this study, we investigated the production of terpenes and isoprene with a focus on Chlamydomonas (Chlorophyceae) and Rhodella maculata (Rhodophyta). Concentrations of terpenes and isoprene were measured using a dynamic headspace (GERSTEL DHS)—gas chromatograph (Agilent 6890N)—mass spectrometer (Agilent 5975C). In addition, chlorophyll a was measured using a fluorometer (Turner TD-700). The results showed that isoprene, α-pinene, and β-pinene were produced by Chlamydomonas sp. and that isoprene, limonene, and camphene were produced by Rhodella maculata. Chlamydomonas sp. produced α-pinene and β-pinene, similar to land plants. The ratio of the pinene/isoprene concentrations in the atmosphere over seawater where phytoplankton are blooming has been reported as approximately 0.7 (Yassaa et al: 2008). In this experiment, the pinene/isoprene concentration ratios in the cultures were approximately 0.1. This result indicates that marine phytoplankton may not be ignored in the marine atmosphere chemistry of terpenes.

  20. Chemistry and biology of terpene trilactones from Ginkgo biloba.

    Science.gov (United States)

    Strømgaard, Kristian; Nakanishi, Koji

    2004-03-19

    Ginkgo biloba, the ginkgo tree, is the oldest living tree, with a long history of use in traditional Chinese medicine. In recent years, the leaf extracts have been widely sold as phytomedicine in Europe and as a dietary supplement worldwide. Effects of Ginkgo biloba extracts have been postulated to include improvement of memory, increased blood circulation, as well as beneficial effects to sufferers of Alzheimer's disease. The most unique components of the extracts are the terpene trilactones, that is, ginkgolides and bilobalide. These structurally complex molecules have been attractive targets for total synthesis. Terpene trilactones are believed to be partly responsible for the neuromodulatory properties of Ginkgo biloba extracts, and several biological effects of the terpene trilactones have been discovered in recent years, making them attractive pharmacological tools that could provide insight into the effects of Ginkgo biloba extracts.

  1. Menthol differs from other terpenic essential oil constituents.

    Science.gov (United States)

    Kolassa, Norbert

    2013-02-01

    The European Medicines Agency concluded that there is a risk of suppositories containing terpenic derivatives, which are used to treat coughs and colds, inducing neurological disorders, especially convulsions, in infants and small children. Terpenic derivatives are found in essential oils obtained from plants and include camphor, eucalyptol (syn. 1,8-cineol), thujone, and menthol. Chemistry, pharmacodynamics and pharmacokinetics of these compounds are clearly different and explain the appearance of convulsions following camphor, thujone, and eucalyptus oil overdose/poisoning, whereas no convulsions have been reported in cases of menthol overdose/poisoning in accordance with the pharmacological properties of menthol. Thus, a general verdict on all terpenic derivatives without differentiation appears inappropriate. Copyright © 2012 Elsevier Inc. All rights reserved.

  2. Functional and evolutionary relationships between terpene synthases from Australian Myrtaceae.

    Science.gov (United States)

    Keszei, Andras; Brubaker, Curt L; Carter, Richard; Köllner, Tobias; Degenhardt, Jörg; Foley, William J

    2010-06-01

    Myrtaceae is one of the chemically most variable and most significant essential oil yielding plant families. Despite an abundance of chemical information, very little work has focussed on the biochemistry of terpene production in these plants. We describe 70 unique partial terpene synthase transcripts and eight full-length cDNA clones from 21 myrtaceous species, and compare phylogenetic relationships and leaf oil composition to reveal clades defined by common function. We provide further support for the correlation between function and phylogenetic relationships by the first functional characterisation of terpene synthases from Myrtaceae: a 1,8-cineole synthase from Eucalyptus sideroxylon and a caryophyllene synthase from Eucalyptusdives. Copyright 2010 Elsevier Ltd. All rights reserved.

  3. The organ-specific expression of terpene synthase genes contributes to the terpene hydrocarbon composition of chamomile essential oils.

    Science.gov (United States)

    Irmisch, Sandra; Krause, Sandra T; Kunert, Grit; Gershenzon, Jonathan; Degenhardt, Jörg; Köllner, Tobias G

    2012-06-08

    The essential oil of chamomile, one of the oldest and agronomically most important medicinal plant species in Europe, has significant antiphlogistic, spasmolytic and antimicrobial activities. It is rich in chamazulene, a pharmaceutically active compound spontaneously formed during steam distillation from the sesquiterpene lactone matricine. Chamomile oil also contains sesquiterpene alcohols and hydrocarbons which are produced by the action of terpene synthases (TPS), the key enzymes in constructing terpene carbon skeletons. Here, we present the identification and characterization of five TPS enzymes contributing to terpene biosynthesis in chamomile (Matricaria recutita). Four of these enzymes were exclusively expressed in above-ground organs and produced the common terpene hydrocarbons (-)-(E)-β-caryophyllene (MrTPS1), (+)-germacrene A (MrTPS3), (E)-β-ocimene (MrTPS4) and (-)-germacrene D (MrTPS5). A fifth TPS, the multiproduct enzyme MrTPS2, was mainly expressed in roots and formed several Asteraceae-specific tricyclic sesquiterpenes with (-)-α-isocomene being the major product. The TPS transcript accumulation patterns in different organs of chamomile were consistent with the abundance of the corresponding TPS products isolated from these organs suggesting that the spatial regulation of TPS gene expression qualitatively contribute to terpene composition. The terpene synthases characterized in this study are involved in the organ-specific formation of essential oils in chamomile. While the products of MrTPS1, MrTPS2, MrTPS4 and MrTPS5 accumulate in the oils without further chemical alterations, (+)-germacrene A produced by MrTPS3 accumulates only in trace amounts, indicating that it is converted into another compound like matricine. Thus, MrTPS3, but also the other TPS genes, are good markers for further breeding of chamomile cultivars rich in pharmaceutically active essential oils.

  4. The organ-specific expression of terpene synthase genes contributes to the terpene hydrocarbon composition of chamomile essential oils

    Directory of Open Access Journals (Sweden)

    Irmisch Sandra

    2012-06-01

    Full Text Available Abstract Background The essential oil of chamomile, one of the oldest and agronomically most important medicinal plant species in Europe, has significant antiphlogistic, spasmolytic and antimicrobial activities. It is rich in chamazulene, a pharmaceutically active compound spontaneously formed during steam distillation from the sesquiterpene lactone matricine. Chamomile oil also contains sesquiterpene alcohols and hydrocarbons which are produced by the action of terpene synthases (TPS, the key enzymes in constructing terpene carbon skeletons. Results Here, we present the identification and characterization of five TPS enzymes contributing to terpene biosynthesis in chamomile (Matricaria recutita. Four of these enzymes were exclusively expressed in above-ground organs and produced the common terpene hydrocarbons (−-(E-β-caryophyllene (MrTPS1, (+-germacrene A (MrTPS3, (E-β-ocimene (MrTPS4 and (−-germacrene D (MrTPS5. A fifth TPS, the multiproduct enzyme MrTPS2, was mainly expressed in roots and formed several Asteraceae-specific tricyclic sesquiterpenes with (−-α-isocomene being the major product. The TPS transcript accumulation patterns in different organs of chamomile were consistent with the abundance of the corresponding TPS products isolated from these organs suggesting that the spatial regulation of TPS gene expression qualitatively contribute to terpene composition. Conclusions The terpene synthases characterized in this study are involved in the organ-specific formation of essential oils in chamomile. While the products of MrTPS1, MrTPS2, MrTPS4 and MrTPS5 accumulate in the oils without further chemical alterations, (+-germacrene A produced by MrTPS3 accumulates only in trace amounts, indicating that it is converted into another compound like matricine. Thus, MrTPS3, but also the other TPS genes, are good markers for further breeding of chamomile cultivars rich in pharmaceutically active essential oils.

  5. SNARE-RNAi results in higher terpene emission from ectopically expressed caryophyllene synthase in nicotiana benthamiana

    NARCIS (Netherlands)

    Ting, Jimmy; Delatte, Thierry L.; Kolkman, P.; Misas-Villamil, Johana C.; Hoorn, Van Der Renier A.L.; Bouwmeester, Harro J.; Krol, van der Sander

    2015-01-01

    Plants produce numerous terpenes and much effort has been dedicated to the identification and characterization of the terpene biosynthetic genes. However, little is known about how terpenes are transported within the cell and from the cell into the apoplast. To investigate a putative role of

  6. Development of next generation biogas cleaning and upgrading technology: demonstration of terpene removal

    NARCIS (Netherlands)

    Linders, M.J.G.; Ham, L.V. van der; Stille, L.C.; Trap, H.C.; Huigen, L.; Mooijer, J.; Goetheer, E.L.V.

    2015-01-01

    Terpenes are a problem for biogas producers, as grid owners will refuse entry to the natural gas grid when more than a few ppm terpenes are detected in the renewable natural gas injected. The problems are related to the integrity of pipelines, safety at the upgrading plant and the fact that terpenes

  7. Simultaneous Determination of Flavonols and Terpene Lactones in ...

    African Journals Online (AJOL)

    Results: The method showed high selectivity of the flavonols and terpene lactones in plasma samples. ... the Control of Pharmaceutical and Biological. Products .... Stability. The stability experiments aimed at testing samples under all possible conditions the samples might experience after collection and prior to analysis.

  8. Extraction, Purification, and NMR Analysis of Terpenes from Brown Algae.

    Science.gov (United States)

    Gaysinski, Marc; Ortalo-Magné, Annick; Thomas, Olivier P; Culioli, Gérald

    2015-01-01

    Algal terpenes constitute a wide and well-documented group of marine natural products with structures differing from their terrestrial plant biosynthetic analogues. Amongst macroalgae, brown seaweeds are considered as one of the richest source of biologically and ecologically relevant terpenoids. These metabolites, mostly encountered in algae of the class Phaeophyceae, are mainly diterpenes and meroditerpenes (metabolites of mixed biogenesis characterized by a toluquinol or a toluquinone nucleus linked to a diterpene moiety).In this chapter, we describe analytical processes commonly employed for the isolation and structural characterization of the main terpenoid constituents obtained from organic extracts of brown algae. The successive steps include (1) extraction of lipidic content from algal samples; (2) purification of terpenes by column chromatography and semi-preparative high-performance liquid chromatography; and (3) structure elucidation of the isolated terpenes by means of 1D and 2D nuclear magnetic resonance (NMR). More precisely, we propose a representative methodology which allows the isolation and structural determination of the monocyclic meroditerpene methoxybifurcarenone (MBFC) from the Mediterranean brown alga Cystoseira amentacea var. stricta. This methodology has a large field of applications and can then be extended to terpenes isolated from other species of the family Sargassaceae.

  9. Transfer of Orally Administered Terpenes in Goat Milk and Cheese

    Directory of Open Access Journals (Sweden)

    I. Poulopoulou

    2012-10-01

    Full Text Available The objective of the present study was to investigate the relationships between terpenes’ intake and their presence in animal tissues (blood and milk as well as in the final product (cheese. Eight dairy goats were divided in two balanced groups, representing control (C and treatment (T group. In T group oral administration of a mixture of terpenes (α-pinene, limonene and β-caryophyllene was applied over a period of 18 d. Cheese was produced, from C and T groups separately, on three time points, twice during the period of terpenes’ oral administration and once after the end of experiment. Terpenes were identified in blood by extraction using petroleum ether and in milk and cheese by the use of solid phase micro-extraction (SPME method, followed by GC-MS analysis. Chemical properties of the milk and the produced cheeses were analyzed and found not differing between the two groups. Limonene and α-pinene were found in all blood and milk samples of the T group after a lag-phase of 3 d, while β-caryophyllene was determined only in few milk samples. Moreover, none of the terpenes were traced in blood and milk of C animals. In cheese, terpenes’ concentrations presented a more complicated pattern implying that terpenes may not be reliable feed tracers. We concluded that monoterpenes can be regarded as potential feed tracers for authentification of goat milk, but further research is required on factors affecting their transfer.

  10. Vanadium haloperoxidase-catalyzed bromination and cyclization of terpenes.

    Science.gov (United States)

    Carter-Franklin, Jayme N; Parrish, Jon D; Tschirret-Guth, Richard A; Little, R Daniel; Butler, Alison

    2003-04-02

    Marine red algae (Rhodophyta) are a rich source of bioactive halogenated natural products, including cyclic terpenes. The biogenesis of certain cyclic halogenated marine natural products is thought to involve marine haloperoxidase enzymes. Evidence is presented that vanadium bromoperoxidase (V-BrPO) isolated and cloned from marine red algae that produce halogenated compounds (e.g., Plocamium cartilagineum, Laurencia pacifica, Corallina officinalis) can catalyze the bromination and cyclization of terpenes and terpene analogues. The V-BrPO-catalyzed reaction with the monoterpene nerol in the presence of bromide ion and hydrogen peroxide produces a monobromo eight-membered cyclic ether similar to laurencin, a brominated C15 acetogenin, from Laurencia glandulifera, along with noncyclic bromohydrin, epoxide, and dibromoproducts; however, reaction of aqueous bromine with nerol produced only noncyclic bromohydrin, epoxide, and dibromoproducts. The V-BrPO-catalyzed reaction with geraniol in the presence of bromide ion and hydrogen peroxide produces two singly brominated six-membered cyclic products, analogous to the ring structures of alpha and beta snyderols, brominated sesquiterpenes from Laurencia, spp., along with noncyclic bromohydrin, epoxide, and dibromoproducts; again, reaction of geraniol with aqueous bromine produces only noncyclic bromohydrin, epoxide, and dibromoproducts. Thus, V-BrPO can direct the electrophilic bromination and cyclization of terpenes.

  11. Biotransformation of geosmin by terpene-degrading bacteria.

    Science.gov (United States)

    Two terpene-degrading bacteria that are able to transform geosmin have been identified. Pseudomonas sp. SBR3-tpnb, isolated on -terpinene, converts geosmin to several products; the major products are keto-geosmins. This geosmin transformation ability is inducible by -terpinene. Rhodococcus wratisl...

  12. REVIEW: Epistasis and dominance in the emergence of catalytic function as exemplified by the evolution of plant terpene synthases.

    Science.gov (United States)

    Cheema, Jitender; Faraldos, Juan A; O'Maille, Paul E

    2017-02-01

    Epistasis, the interaction between mutations and the genetic background, is a pervasive force in evolution that is difficult to predict yet derives from a simple principle - biological systems are interconnected. Therefore, one effect may be intimately linked to another, hence interdependent. Untangling epistatic interactions between and within genes is a vibrant area of research. Deriving a mechanistic understanding of epistasis is a major challenge. Particularly, elucidating how epistasis can attenuate the effects of otherwise dominant mutations that control phenotypes. Using the emergence of terpene cyclization in specialized metabolism as an excellent example, this review describes the process of discovery and interpretation of dominance and epistasis in relation to current efforts. Specifically, we outline experimental approaches to isolating epistatic networks of mutations in protein structure, formally quantifying epistatic interactions, then building biochemical models with chemical mechanisms in efforts to achieve an understanding of the physical basis for epistasis. From these models we describe informed conjectures about past evolutionary events that underlie the emergence, divergence and specialization of terpene synthases to illustrate key principles of the constraining forces of epistasis in enzyme function. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  13. Progress in renewable polymers from natural terpenes, terpenoids, and rosin.

    Science.gov (United States)

    Wilbon, Perry A; Chu, Fuxiang; Tang, Chuanbing

    2013-01-11

    The development of sustainable renewable polymers from natural resources has increasingly gained attention from scientists, engineers as well as the general public and government agencies. This review covers recent progress in the field of renewable bio-based monomers and polymers from natural resources: terpenes, terpenoids, and rosin, which are a class of hydrocarbon-rich biomass with abundance and low cost, holding much potential for utilization as organic feedstocks for green plastics and composites. This review details polymerization and copolymerization of terpenes such as pinene, limonene, and myrcene and their derivatives, terpenoids including carvone and menthol, and rosin-derived monomers. The future direction on the utilization of these natural resources is discussed. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Mechanistic chemistry of oxidation of balsalazide with acidic ...

    Indian Academy of Sciences (India)

    and pharmaceutical dosage forms.3–6 But so far no research work has been carried out on the oxidation of this drug with any oxidants viewed from the kinetic and mechanistic viewpoints. The in vitro kinetic results would be very useful to kineticists who are working on the kinetic and mechanistic chemistry of BSZ drug in.

  15. Isolation and characterization of terpene synthases in cotton (Gossypium hirsutum).

    Science.gov (United States)

    Yang, Chang-Qing; Wu, Xiu-Ming; Ruan, Ju-Xin; Hu, Wen-Li; Mao, Yin-Bo; Chen, Xiao-Ya; Wang, Ling-Jian

    2013-12-01

    Cotton plants accumulate gossypol and related sesquiterpene aldehydes, which function as phytoalexins against pathogens and feeding deterrents to herbivorous insects. However, to date little is known about the biosynthesis of volatile terpenes in this crop. Herein is reported that 5 monoterpenes and 11 sesquiterpenes from extracts of a glanded cotton cultivar, Gossypium hirsutum cv. CCRI12, were detected by gas chromatography-mass spectrometry (GC-MS). By EST data mining combined with Rapid Amplification of cDNA Ends (RACE), full-length cDNAs of three terpene synthases (TPSs), GhTPS1, GhTPS2 and GhTPS3 were isolated. By in vitro assays of the recombinant proteins, it was found that GhTPS1 and GhTPS2 are sesquiterpene synthases: the former converted farnesyl pyrophosphate (FPP) into β-caryophyllene and α-humulene in a ratio of 2:1, whereas the latter produced several sesquiterpenes with guaia-1(10),11-diene as the major product. By contrast, GhTPS3 is a monoterpene synthase, which produced α-pinene, β-pinene, β-phellandrene and trace amounts of other monoterpenes from geranyl pyrophosphate (GPP). The TPS activities were also supported by Virus Induced Gene Silencing (VIGS) in the cotton plant. GhTPS1 and GhTPS3 were highly expressed in the cotton plant overall, whereas GhTPS2 was expressed only in leaves. When stimulated by mechanical wounding, Verticillium dahliae (Vde) elicitor or methyl jasmonate (MeJA), production of terpenes and expression of the corresponding synthase genes were induced. These data demonstrate that the three genes account for the biosynthesis of volatile terpenes of cotton, at least of this Upland cotton. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Esterification and etherification of steroid and terpene under Mitsunobu conditions

    Directory of Open Access Journals (Sweden)

    Samia Guezane Lakoud

    2016-09-01

    Full Text Available The synthesis and study of steroids and terpenes continues to be a topic of widespread interest, the esterification and etherification under Mitsunobu conditions of primary alcohol such as geraniol prepared in 95% yield, and when a chiral secondary alcohol such as cholesterol or menthol is used, sufficient configurational inversion of alcohol with 65% yield, but the reaction of tertiary alcohols the α-terpeniol for example are rare.

  17. Catalytic Synthesis and Antifungal Activity of New Polychlorinated Natural Terpenes

    Directory of Open Access Journals (Sweden)

    Hana Ighachane

    2017-01-01

    Full Text Available Various unsaturated natural terpenes were selectively converted to the corresponding polychlorinated products in good yields using iron acetylacetonate in combination with nucleophilic cocatalyst. The synthesized compounds were evaluated for their in vitro antifungal activity. The antifungal bioassays showed that 2c and 2d possessed significant antifungal activity against Fusarium oxysporum f. sp. albedinis (Foa, Fusarium oxysporum f. sp. canariensis (Foc, and Verticillium dahliae (Vd.

  18. Structural determinants of reductive terpene cyclization in iridoid biosynthesis

    DEFF Research Database (Denmark)

    Kries, Hajo; Caputi, Lorenzo; Stevenson, Clare E M

    2016-01-01

    The carbon skeleton of ecologically and pharmacologically important iridoid monoterpenes is formed in a reductive cyclization reaction unrelated to canonical terpene cyclization. Here we report the crystal structure of the recently discovered iridoid cyclase (from Catharanthus roseus) bound...... to a mechanism-inspired inhibitor that illuminates substrate binding and catalytic function of the enzyme. Key features that distinguish iridoid synthase from its close homolog progesterone 5β-reductase are highlighted....

  19. Derivatization Technique To Identify Specifically Carbonyl Groups by Infrared Spectroscopy: Characterization of Photooxidative Aging Products in Terpenes and Terpeneous Resins.

    Science.gov (United States)

    Zumbühl, Stefan; Brändle, Andreas; Hochuli, Andreas; Scherrer, Nadim C; Caseri, Walter

    2017-02-07

    Analysis of bioorganic materials by infrared spectroscopy (FT-IR) is frequently limited due to overlapping of diagnostic bands from the various components, which poses a fundamental problem to this analytical technique. The distinction of oxidized di- and triterpenes, for example, is hindered by the superposition of similar absorption bands of carbonyl functional groups summing up to a broad, nondistinctive signal. This study presents a technique for selective fluorination of various carboxylic acids by exposure to gaseous sulfur tetrafluoride. The derivatization treatment leads to characteristic band shifts, allowing the separation of otherwise overlapping bands. Accordingly, the IR bands of primary acids, α,β-unsaturated acids, tertiary acids, peroxy acids, esters, ketones, and α,β-unsaturated ketones are split into distinct absorption bands. The capability of this method is demonstrated on the example of natural resins and their ingredients, which are commonly known to be susceptible to oxidation at ambient conditions. The derivatization method enables one to identify various carbonyl containing functional groups by infrared spectroscopy, even in complex mixtures of terpenes. It unveils previously hidden degradation reactions running in terpenes and natural resins exposed to artificial aging by irradiation with light. New insight is presented on the individual reaction pathways of the terpenes hydroxydammarenone and abietic acid as well as of natural resin varnishes made from dammar and colophony.

  20. Induced Terpene Accumulation in Norway Spruce Inhibits Bark Beetle Colonization in a Dose-Dependent Manner

    Science.gov (United States)

    Zhao, Tao; Krokene, Paal; Hu, Jiang; Christiansen, Erik; Björklund, Niklas; Långström, Bo; Solheim, Halvor; Borg-Karlson, Anna-Karin

    2011-01-01

    Background Tree-killing bark beetles (Coleoptera, Scolytinae) are among the most economically and ecologically important forest pests in the northern hemisphere. Induction of terpenoid-based oleoresin has long been considered important in conifer defense against bark beetles, but it has been difficult to demonstrate a direct correlation between terpene levels and resistance to bark beetle colonization. Methods To test for inhibitory effects of induced terpenes on colonization by the spruce bark beetle Ips typographus (L.) we inoculated 20 mature Norway spruce Picea abies (L.) Karsten trees with a virulent fungus associated with the beetle, Ceratocystis polonica (Siem.) C. Moreau, and investigated induced terpene levels and beetle colonization in the bark. Results Fungal inoculation induced very strong and highly variable terpene accumulation 35 days after inoculation. Trees with high induced terpene levels (n = 7) had only 4.9% as many beetle attacks (5.1 vs. 103.5 attacks m−2) and 2.6% as much gallery length (0.029 m m−2 vs. 1.11 m m−2) as trees with low terpene levels (n = 6). There was a highly significant rank correlation between terpene levels at day 35 and beetle colonization in individual trees. The relationship between induced terpene levels and beetle colonization was not linear but thresholded: above a low threshold concentration of ∼100 mg terpene g−1 dry phloem trees suffered only moderate beetle colonization, and above a high threshold of ∼200 mg terpene g−1 dry phloem trees were virtually unattacked. Conclusion/Significance This is the first study demonstrating a dose-dependent relationship between induced terpenes and tree resistance to bark beetle colonization under field conditions, indicating that terpene induction may be instrumental in tree resistance. This knowledge could be useful for developing management strategies that decrease the impact of tree-killing bark beetles. PMID:22028932

  1. Isolation and screening of microorganisms with potential for biotransformation of terpenic substrates

    OpenAIRE

    Bier,Mário César Jucoski; Poletto,Sabrina; Soccol,Vanete Thomaz; Soccol,Carlos Ricardo; Medeiros,Adriane Bianchi Pedroni

    2011-01-01

    The objective of the present work was to isolate and select strains with potential to perform the biotransformation of terpenic substrates. Microorganisms obtained from a collection culture and also isolated from a natural source of terpene substrate were tested. Seventeen strains were selected by their resistance to terpenes in potato dextrose agar containing up to 1% of limonene or α-pinene and β-pinene (1:1). Subsequently, 10 strains were selected by their capacity of using these...

  2. Induced terpene accumulation in Norway spruce inhibits bark beetle colonization in a dose-dependent manner.

    Directory of Open Access Journals (Sweden)

    Tao Zhao

    Full Text Available Tree-killing bark beetles (Coleoptera, Scolytinae are among the most economically and ecologically important forest pests in the northern hemisphere. Induction of terpenoid-based oleoresin has long been considered important in conifer defense against bark beetles, but it has been difficult to demonstrate a direct correlation between terpene levels and resistance to bark beetle colonization.To test for inhibitory effects of induced terpenes on colonization by the spruce bark beetle Ips typographus (L. we inoculated 20 mature Norway spruce Picea abies (L. Karsten trees with a virulent fungus associated with the beetle, Ceratocystis polonica (Siem. C. Moreau, and investigated induced terpene levels and beetle colonization in the bark.Fungal inoculation induced very strong and highly variable terpene accumulation 35 days after inoculation. Trees with high induced terpene levels (n = 7 had only 4.9% as many beetle attacks (5.1 vs. 103.5 attacks m(-2 and 2.6% as much gallery length (0.029 m m(-2 vs. 1.11 m m(-2 as trees with low terpene levels (n = 6. There was a highly significant rank correlation between terpene levels at day 35 and beetle colonization in individual trees. The relationship between induced terpene levels and beetle colonization was not linear but thresholded: above a low threshold concentration of ∼100 mg terpene g(-1 dry phloem trees suffered only moderate beetle colonization, and above a high threshold of ∼200 mg terpene g(-1 dry phloem trees were virtually unattacked.This is the first study demonstrating a dose-dependent relationship between induced terpenes and tree resistance to bark beetle colonization under field conditions, indicating that terpene induction may be instrumental in tree resistance. This knowledge could be useful for developing management strategies that decrease the impact of tree-killing bark beetles.

  3. Actividad antimicobacteriana de terpenos Antimycobacterial activity of terpenes

    Directory of Open Access Journals (Sweden)

    Juan Gabriel Bueno-Sánchez

    2009-12-01

    Full Text Available Introducción: La tuberculosis (TB, causada por Mycobacterium tuberculosis es la mayor causa de mortalidad mundial por un único agente patógeno. Asimismo, un gran número de micobacterias no tuberculosas, especialmente M. avium, M. intracellulare y M. chelonae, causan infecciones oportunistas en pacientes con SIDA. Muchos terpenos poseen actividad biológica y se emplean en el tratamiento de diversas enfermedades, razón que los hace fuente de moléculas promisorias. Objetivo: El objetivo del presente estudio fue determinar la actividad antimicobacteriana de 16 terpenos contra M. tuberculosis H37Rv y un aislamiento clínico de M. chelonae. Materiales y métodos: Se obtuvo la concentración mínima inhibitoria (CMI de los mismos y se realizaron curvas de letalidad para establecer actividad bactericida, empleando una técnica de macrodilución en caldo estandarizada para este tipo de compuestos volátiles. Resultados: Los terpenos con menor valor de CMI fueron timol y carvacrol, con concentraciones de 125-250 μg/mL, y actividad bactericida contra los dos microorganismos. Geraniol, mirceno, ρ-cimeno, alfa-pineno, presentaron valores de CMI entre 250 y 500 μg/mL. Conclusiones: Algunos terpenos han presentado actividad importante contra microorganismos del género Mycobacterium, sin embargo los valores de CMI obtenidos no explican el efecto antimicrobiano presentado por el aceite completo, se requiere evaluar las interacciones de sinergismo y/o antagonismo entre los terpenos para determinar los componentes responsables de la acción farmacológica. Salud UIS 2009; 41: 231-235Introduction: Tuberculosis (TB caused by Mycobacterium tuberculosis is the major source of global mortality from a single pathogen. Moreover, a large number of nontuberculous mycobacteria, especially M. avium, M. intracellulare and M. chelonae, cause opportunistic infection in AIDS patients. Terpenes, possess a wide spectrum of biological activity and are used in the

  4. Terpenes as Green Solvents for Extraction of Oil from Microalgae

    Directory of Open Access Journals (Sweden)

    Celine Dejoye Tanzi

    2012-07-01

    Full Text Available Herein is described a green and original alternative procedure for the extraction of oil from microalgae. Extractions were carried out using terpenes obtained from renewable feedstocks as alternative solvents instead of hazardous petroleum solvents such as n-hexane. The described method is achieved in two steps using Soxhlet extraction followed by the elimination of the solvent from the medium using Clevenger distillation in the second step. Oils extracted from microalgae were compared in terms of qualitative and quantitative determination. No significant difference was obtained between each extract, allowing us to conclude that the proposed method is green, clean and efficient.

  5. Terpenes as green solvents for extraction of oil from microalgae.

    Science.gov (United States)

    Dejoye Tanzi, Celine; Abert Vian, Maryline; Ginies, Christian; Elmaataoui, Mohamed; Chemat, Farid

    2012-07-09

    Herein is described a green and original alternative procedure for the extraction of oil from microalgae. Extractions were carried out using terpenes obtained from renewable feedstocks as alternative solvents instead of hazardous petroleum solvents such as n-hexane. The described method is achieved in two steps using Soxhlet extraction followed by the elimination of the solvent from the medium using Clevenger distillation in the second step. Oils extracted from microalgae were compared in terms of qualitative and quantitative determination. No significant difference was obtained between each extract, allowing us to conclude that the proposed method is green, clean and efficient.

  6. Terpenes of Salvia species leaf oils: chemosystematic implications

    OpenAIRE

    Coassini Lokar, Laura; Moneghini, Mariarosa

    2017-01-01

    Wild specimens of Salvia L. were collected in three different moments of anthesis and their volatile leaf oils were analyzed by GC/GCMS. The quantitative terpene composition is very variable with the anthesis. S. bertolonii is the richest species in a-thujone. S. officinalis is characterized by high percentages of 1,8 cineole, 4-terpineol, isorboneol and a -bisabolol. In S. verticillata high percentages of borneol and {3-cariophyllene are present. In the three species a-thujone was always mor...

  7. Determination of the terpene flux from orange species and Norway spruce by relaxed eddy accumulation

    DEFF Research Database (Denmark)

    Christensen, C.S.; Hummelshøj, P.; Jensen, N.O.

    2000-01-01

    Terpene fluxes from a Norway spruce (Picea abies) forest and an orange orchard (Citrus clementii and Citrus sinensis) were measured by relaxed eddy accumulation (REA) during summer 1997. alpha-pinene and beta-pinene were the most abundant terpenes emitted from Norway spruce and constituted...

  8. Production of alpha-cuprenene in Xanthophyllomyces dendrorhous : a step closer to a potent terpene biofactory

    NARCIS (Netherlands)

    Melillo, Elena; Setroikromo, Rita; Quax, Wim J.; Kayser, Oliver

    2013-01-01

    Background: The red yeast Xanthophyllomyces dendrorhous is a natural producer of the carotenoid astaxanthin. Because of its high flux, the native terpene pathway leading to the production of the tetraterpene is of particular interest as it can be redirected toward the production of other terpene

  9. 40 CFR 721.7020 - Distillates (petroleum), C(3-6), polymers with styrene and mixed terpenes (generic name).

    Science.gov (United States)

    2010-07-01

    ...), polymers with styrene and mixed terpenes (generic name). 721.7020 Section 721.7020 Protection of...), C(3-6), polymers with styrene and mixed terpenes (generic name). (a) Chemical substance and...), polymers with styrene and mixed terpenes (PMN P-89-676) is subject to reporting under this section for the...

  10. A high-throughput colorimetric screening assay for terpene synthase activity based on substrate consumption.

    Directory of Open Access Journals (Sweden)

    Maiko Furubayashi

    Full Text Available Terpene synthases catalyze the formation of a variety of terpene chemical structures. Systematic mutagenesis studies have been effective in providing insights into the characteristic and complex mechanisms of C-C bond formations and in exploring the enzymatic potential for inventing new chemical structures. In addition, there is growing demand to increase terpene synthase activity in heterologous hosts, given the maturation of metabolic engineering and host breeding for terpenoid synthesis. We have developed a simple screening method for the cellular activities of terpene synthases by scoring their substrate consumption based on the color loss of the cell harboring carotenoid pathways. We demonstrate that this method can be used to detect activities of various terpene synthase or prenyltransferase genes in a high-throughput manner, irrespective of the product type, enabling the mutation analysis and directed evolution of terpene synthases. We also report the possibility for substrate-specific screening system of terpene synthases by taking advantage of the substrate-size specificity of C30 and C40 carotenoid pathways.

  11. Population divergence in the ontogenetic trajectories of foliar terpenes of a Eucalyptus species

    Science.gov (United States)

    Borzak, Christina L.; Potts, Brad M.; Davies, Noel W.; O’Reilly-Wapstra, Julianne M.

    2015-01-01

    Background and Aims The development of plant secondary metabolites during early life stages can have significant ecological and evolutionary implications for plant–herbivore interactions. Foliar terpenes influence a broad range of ecological interactions, including plant defence, and their expression may be influenced by ontogenetic and genetic factors. This study investigates the role of these factors in the expression of foliar terpene compounds in Eucalyptus globulus seedlings. Methods Seedlings were sourced from ten families each from three genetically distinct populations, representing relatively high and low chemical resistance to mammalian herbivory. Cotyledon-stage seedlings and consecutive leaf pairs of true leaves were harvested separately across an 8-month period, and analysed for eight monoterpene compounds and six sesquiterpene compounds. Key Results Foliar terpenes showed a series of dynamic changes with ontogenetic trajectories differing between populations and families, as well as between and within the two major terpene classes. Sesquiterpenes changed rapidly through ontogeny and expressed opposing trajectories between compounds, but showed consistency in pattern between populations. Conversely, changed expression in monoterpene trajectories was population- and compound-specific. Conclusions The results suggest that adaptive opportunities exist for changing levels of terpene content through ontogeny, and evolution may exploit the ontogenetic patterns of change in these compounds to create a diverse ontogenetic chemical mosaic with which to defend the plant. It is hypothesized that the observed genetically based patterns in terpene ontogenetic trajectories reflect multiple changes in the regulation of genes throughout different terpene biosynthetic pathways. PMID:25434028

  12. Terpene chemodiversity of relict conifers Picea omorika, Pinus heldreichii, and Pinus peuce, endemic to Balkan.

    Science.gov (United States)

    Nikolić, Biljana; Ristić, Mihailo; Tešević, Vele; Marin, Petar D; Bojović, Srdjan

    2011-12-01

    Terpenes are often used as ecological and chemotaxonomic markers of plant species, as well as for estimation of geographic variability. Essential oils of relic and Balkan endemic/subendemic conifers, Picea omorika, Pinus heldreichii, and P. peuce, in central part of Balkan Peninsula (Serbia and Montenegro), on the level of terpene classes and common terpene compounds were investigated. In finding terpene combinations, which could show the best diversity between species and their natural populations, several statistical methods were applied. Apart from the content of different terpene classes (P. omorika has the most abundant O-containing monoterpenes and sesquiterpenes; P. heldreichii and P. peuce have the largest abundance of sesquiterpene and monoterpene hydrocarbons, resp.), the species are clearly separated according to terpene profile with 22 common compounds. But, divergences in their populations were established only in combination of several compounds (specific for each species), and they were found to be the results of geomorphologic, climatic, and genetic factors. We found similarities between investigated species and some taxa from literature with respect to terpene composition, possibly due to hybridization and phylogenetic relations. Obtained results are also important regarding to chemotaxonomy, biogeography, phylogeny, and evolution of these taxa. Copyright © 2011 Verlag Helvetica Chimica Acta AG, Zürich.

  13. Ex vivo skin absorption of terpenes from Vicks VapoRub ointment.

    Science.gov (United States)

    Cal, Krzysztof; Sopala, Monika

    2008-08-01

    The pharmaceutical market offers a wide range of inhalant drug products applied on the skin that contain essential oils and/or their isolated compounds, i.e. terpenes. Because there are few data concerning the skin penetration of terpenes, especially from complex carriers, the goal of this study was to determine the ex vivo skin absorption kinetics of chosen terpenes, namely eucalyptol, menthol, camphor, alpha-pinene, and beta-pinene, from the product Vicks VapoRub. Human cadaver skin was placed in a flow-through diffusion chamber and the product was applied for 15, 30, and 60 min. After the application time the skin was separated into layers using a tape-stripping technique: three fractions of stratum corneum and epidermis with dermis, and terpenes amounts in the samples were determined by gas-chromatography. The investigated terpenes showed different absorption characteristics related to their physicochemical properties and did not permeate through the skin into the acceptor fluid. Eucalyptol had the largest total accumulation in the stratum corneum and in the epidermis with dermis, while alpha-pinene penetrated into the skin in the smallest amount. The short time in which saturation of the stratum corneum with the terpenes occurred and the high accumulation of most of the investigated terpenes in the skin layers proved that these compounds easily penetrate and permeate the stratum corneum and that in vivo they may easily penetrate into the blood circulation.

  14. Transfer of terpenes from essential oils into cow milk

    DEFF Research Database (Denmark)

    Lejonklev, J.; Løkke, M.M.; Larsen, M.K.

    2013-01-01

    The objective of this study was to investigate the transfer of volatile terpenes from caraway seed and oregano plant essential oils into cow's milk through respiratory and gastrointestinal exposure. Essential oils have potential applications as feed additives because of their antimicrobial...... properties, but very little work exists on the transfer of their volatile compounds into milk. Lactating Danish Holstein cows with duodenum cannula were used. Gastrointestinal exposure was facilitated by infusing the essential oils, mixed with deodorized sesame oil, into the duodenum cannula. Two levels were...... tested for each essential oil. Respiratory exposure was facilitated by placing the animal in a chamber together with a sponge soaked in the essential oils. All exposures were spread over 9 h. Milk samples were collected immediately before and after exposure, as well as the next morning. Twelve...

  15. Chemical Components and Pharmacological Activities of Terpene Natural Products from the Genus Paeonia.

    Science.gov (United States)

    Zhao, Dan-Dan; Jiang, Li-Li; Li, Hong-Yi; Yan, Peng-Fei; Zhang, Yan-Long

    2016-10-13

    Paeonia is the single genus of ca. 33 known species in the family Paeoniaceae , found in Asia, Europe and Western North America. Up to now, more than 180 compounds have been isolated from nine species of the genus Paeonia , including terpenes, phenols, flavonoids, essential oil and tannins. Terpenes, the most abundant naturally occurring compounds, which accounted for about 57% and occurred in almost every species, are responsible for the observed in vivo and in vitro biological activities. This paper aims to give a comprehensive overview of the recent phytochemical and pharmacological knowledge of the terpenes from Paeonia plants, and enlighten further drug discovery research.

  16. Chemodiversity in terpene emissions at a boreal Scots pine stand

    Science.gov (United States)

    Bäck, J.; Aalto, J.; Henriksson, M.; Hakola, H.; He, Q.; Boy, M.

    2011-10-01

    Atmospheric chemistry in background areas is strongly influenced by natural vegetation. Coniferous forests are known to produce large quantities of volatile vapors, especially terpenes to the surrounding air. These compounds are reactive in the atmosphere, and contribute to the formation and growth of atmospheric new particles. Our aim was to analyze the variability of mono- and sesquiterpene emissions between Scots pine trees, in order to clarify the potential errors caused by using emission data obtained from only a few trees in atmospheric chemistry models. We also aimed at testing if stand history and seed origin has an influence on the chemotypic diversity. The inherited, chemotypic variability in mono- and sesquiterpene emission was studied in a seemingly homogeneous 47-yr-old stand in Southern Finland, where two areas differing in their stand regeneration history could be distinguished. Sampling was conducted in August 2009. Terpene concentrations in the air had been measured at the same site for seven years prior to branch sampling for chemotypes. Two main compounds, α-pinene and Δ3-carene formed together 40-97% of the monoterpene proportions in both the branch emissions and in the air concentrations. The data showed a bimodal distribution in emission composition, in particular in Δ3-carene emission within the studied population. 10% of the trees emitted mainly α-pinene and no Δ3-carene at all, whereas 20% of the trees where characterized as high Δ3-carene emitters (Δ3-carene forming >80% of total emitted monoterpene spectrum). An intermediate group of trees emitted equal amounts of both α-pinene and Δ3-carene. The emission pattern of trees at the area established using seeding as the artificial regeneration method differed from the naturally regenerated or planted trees, being mainly high Δ3-carene emitters. Some differences were also seen in e.g. camphene and limonene emissions between chemotypes, but sesquiterpene emissions did not differ

  17. Indoor fine particles: the role of terpene emissions from consumer products.

    Science.gov (United States)

    Sarwar, Golam; Olson, David A; Corsi, Richard L; Weschler, Charles J

    2004-03-01

    Consumer products can emit significant quantities of terpenes, which can react with ozone (O3). Resulting byproducts include compounds with low vapor pressures that contribute to the growth of secondary organic aerosols (SOAs). The focus of this study was to evaluate the potential for SOA growth, in the presence of O3, following the use of a lime-scented liquid air freshener, a pine-scented solid air freshener, a lemon-scented general-purpose cleaner, a wood floor cleaner, and a perfume. Two chamber experiments were performed for each of these five terpene-containing agents, one at an elevated O3 concentration and-the other at a lower O3 concentration. Particle number and mass concentrations increased and O3 concentrations decreased during each experiment. Experiments with terpene-based air fresheners produced the highest increases in particle number and mass concentrations. The results of this study clearly demonstrate that homogeneous reactions between O3 and terpenes from various consumer products can lead to increases in fine particle mass concentrations when these products are used indoors. Particle increases can occur during periods of elevated outdoor O3 concentrations or indoor O3 generation, coupled with elevated terpene releases. Human exposure to fine particles can be reduced by minimizing indoor terpene concentrations or O3 concentrations.

  18. Total synthesis of eudesmane terpenes by site-selective C-H oxidations.

    Science.gov (United States)

    Chen, Ke; Baran, Phil S

    2009-06-11

    From menthol to cholesterol to Taxol, terpenes are a ubiquitous group of molecules (over 55,000 members isolated so far) that have long provided humans with flavours, fragrances, hormones, medicines and even commercial products such as rubber. Although they possess a seemingly endless variety of architectural complexities, the biosynthesis of terpenes often occurs in a unified fashion as a 'two-phase' process. In the first phase (the cyclase phase), simple linear hydrocarbon phosphate building blocks are stitched together by means of 'prenyl coupling', followed by enzymatically controlled molecular cyclizations and rearrangements. In the second phase (the oxidase phase), oxidation of alkenes and carbon-hydrogen bonds results in a large array of structural diversity. Although organic chemists have made great progress in developing the logic needed for the cyclase phase of terpene synthesis, particularly in the area of polyene cyclizations, much remains to be learned if the oxidase phase is to be mimicked in the laboratory. Here we show how the logic of terpene biosynthesis has inspired the highly efficient and stereocontrolled syntheses of five oxidized members of the eudesmane family of terpenes in a modicum of steps by a series of simple carbocycle-forming reactions followed by multiple site-selective inter- and intramolecular carbon-hydrogen oxidations. This work establishes an intellectual framework in which to conceive the laboratory synthesis of other complex terpenes using a 'two-phase' approach.

  19. Volatile terpenes from actinomycetes: a biosynthetic study correlating chemical analyses to genome data.

    Science.gov (United States)

    Rabe, Patrick; Citron, Christian A; Dickschat, Jeroen S

    2013-11-25

    The volatile terpenes of 24 actinomycetes whose genomes have been sequenced (or are currently being sequenced) were collected by use of a closed-loop stripping apparatus and identified by GC/MS. The analytical data were compared against a phylogenetic analysis of all 192 currently available sequences of bacterial terpene cyclases (excluding geosmin and 2-methylisoborneol synthases). In addition to the several groups of terpenes with known biosynthetic origin, selinadienes were identified as a large group of biosynthetically related sesquiterpenes that are produced by several streptomycetes. The detection of a large number of previously unrecognised side products of known terpene cyclases proved to be particularly important for an in depth understanding of biosynthetic pathways to known terpenes in actinomycetes. Interpretation of the chemical analytical data in the context of the phylogenetic tree of bacterial terpene cyclases pointed to the function of three new enzymes: (E)-β-caryophyllene synthase, selina-3,7(11)-diene synthase and aristolochene synthase. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Terpene compound drug as medical expulsive therapy for ureterolithiasis: a meta-analysis.

    Science.gov (United States)

    Chua, Michael Erlano; Park, Jane Hyeon; Castillo, Josefino Cortez; Morales, Marcelino Lopeztan

    2013-04-01

    The aim of this study is to investigate the efficacy of terpene compound drug (pinene, camphene, borneol, anethole, fenchone and cineol in olive oil) in facilitating spontaneous passage of ureteral calculi through meta-analysis of randomized controlled trials (RCT). Systematic literature search on MEDLINE, EMBASE, OVID, Science Direct, Proquest, Google scholar, Cochrane Library databases and reference list of related literatures were done without language restriction. RCTs on ureterolithiasis medical expulsive therapy (MET) that compare terpene compound drug versus placebo/control group or alpha-blockers were identified. Articles retrieved were critically appraised by two independent reviewers according to Cochrane Collaboration recommendations. Data from included studies were extracted for calculation of risk ratio (RR) and 95 % confidence interval (CI). Effect estimates were pooled using Mantel-Haenszel method with random effect model. Inter-study heterogeneity and publication bias were assessed. The PRISMA guidelines for meta-analysis reporting were followed. Five RCTs (total of 344 subjects) of adequate methodological quality were included. Pooled effect estimates from homogenous studies showed that compared to placebo/control group, patients treated with terpene compound drug had significantly better ureteral calculi spontaneous expulsion rate (pooled RR: 1.34; 95 % CI 1.12, 1.61). Subgroup analysis of studies that compare terpene compound drug with alpha-blockers showed no significant difference (pooled RR: 0.79; 95 % CI 0.59, 1.06), while significant inter-study heterogeneity was noted. Only minor gastrointestinal adverse effect was reported on terpene compound drug use. The results suggest that terpene compound drug as MET is effective in augmenting spontaneous passage of ureterolithiasis. High quality large-scale RCTs comparing alpha-blockers and terpene compound drug are warranted to make a more definitive conclusion.

  1. Mechanistic studies of olefin metathesis

    Energy Technology Data Exchange (ETDEWEB)

    Grubbs, R.H.

    1979-03-01

    A review covers studies of the olefin metathesis mechanism which indicated that the reaction proceeds by a non-pairwise mechanism; detailed mechanistic studies on the homogeneously and heterogeneously catalyzed metathesis; and stereochemical investigations.

  2. Terpenes : Effect of lipophilicity in enhancing transdermal delivery of alfuzosin hydrochloride.

    Directory of Open Access Journals (Sweden)

    D Prasanthi

    2012-01-01

    Full Text Available Transdermal drug delivery has attracted much attention as an alternative to intravenous and oral methods of delivery. But the main barrier is stratum corneum. Terpenes classes of chemical enhancers are used in transdermal formulations for facilitating penetration of drugs. The aim of the study is to evaluate terpenes as skin penetration enhancers and correlate its relationship with permeation and lipophilicity. In this study, alfuzosin hydrochloride (AH hydrogels were prepared with terpenes using Taguchi orthogonal array experimental design. The formulations contained one of eight terpenes, based on their lipophilicity (log P 2.13-5.36. The percutaneous permeation was studied in rat skin using diffusion cell technique. Flux, cumulative amount, lag time and skin content of AH were measured over 24 hours and compared with control gels. Nerolidol with highest lipophilicity (log P 5.36 ± 0.38 showed highest cumulative amount (Q(24 of 647.29 ± 18.76 μg/cm(2 and fluxrateof 28.16 ± 0.64 μg/cm(2/hour. It showed decreased lag time of 0.76 ± 0.15 hours. Fenchone (2.5% (log P 2.13 ± 0.30 produced the longest lag time 4.8 ± 0.20 hours. The rank order of enhancement effect was shown as nerolidol > farnesol > limonene > linalool > geraniol > carvone > fenchone > menthol. Lowest skin content was seen with carvone. Increase in lipophilicity of terpenes showed increase in flux, cumulative amount (Q(24, and enhancement ratio which was significant with P < 0.000. But lag time was decreased and no correlation was found between lipophilicity and skin content. Histological studies showed changes in dermis which can be attributed to disruption of lipid packing of stratum corneum due to effect of nerolidol within lipid lamellae. It was found that small alcoholic terpenes with high degree of unsaturation enhance permeation of hydrophilic drugs, liquid terpenes enhance better than solid terpenes and terpenes with high lipophilicity are good

  3. Terpenes: Effect of lipophilicity in enhancing transdermal delivery of alfuzosin hydrochloride

    Directory of Open Access Journals (Sweden)

    D Prasanthi

    2012-01-01

    Full Text Available Transdermal drug delivery has attracted much attention as an alternative to intravenous and oral methods of delivery. But the main barrier is stratum corneum. Terpenes classes of chemical enhancers are used in transdermal formulations for facilitating penetration of drugs. The aim of the study is to evaluate terpenes as skin penetration enhancers and correlate its relationship with permeation and lipophilicity. In this study, alfuzosin hydrochloride (AH hydrogels were prepared with terpenes using Taguchi orthogonal array experimental design. The formulations contained one of eight terpenes, based on their lipophilicity (log P 2.13-5.36. The percutaneous permeation was studied in rat skin using diffusion cell technique. Flux, cumulative amount, lag time and skin content of AH were measured over 24 hours and compared with control gels. Nerolidol with highest lipophilicity (log P 5.36 ± 0.38 showed highest cumulative amount (Q 24 of 647.29 ± 18.76 μg/cm 2 and fluxrateof 28.16 ± 0.64 μg/cm 2 /hour. It showed decreased lag time of 0.76 ± 0.15 hours. Fenchone (2.5% (log P 2.13 ± 0.30 produced the longest lag time 4.8 ± 0.20 hours. The rank order of enhancement effect was shown as nerolidol > farnesol > limonene > linalool > geraniol > carvone > fenchone > menthol. Lowest skin content was seen with carvone. Increase in lipophilicity of terpenes showed increase in flux, cumulative amount (Q 24 , and enhancement ratio which was significant with P < 0.000. But lag time was decreased and no correlation was found between lipophilicity and skin content. Histological studies showed changes in dermis which can be attributed to disruption of lipid packing of stratum corneum due to effect of nerolidol within lipid lamellae. It was found that small alcoholic terpenes with high degree of unsaturation enhance permeation of hydrophilic drugs, liquid terpenes enhance better than solid terpenes and terpenes with high lipophilicity are good penetration

  4. Seasonal variations in terpene emission factors of dominant species in four ecosystems in NE Spain

    Science.gov (United States)

    Llusia, Joan; Peñuelas, Josep; Guenther, Alex; Rapparini, Francesca

    2013-05-01

    We studied the daily patterns in the rates of foliar terpene emissions by four typical species from the Mediterranean region in two days of early spring and two days of summer in 4 localities of increasing biomass cover in Northern Spain. The species studied were Thymelaea tinctoria (in Monegros), Quercus coccifera (in Garraf), Quercus ilex (in Prades) and Fagus sylvatica (in Montseny). Of the total 43 VOCs detected, 23 were monoterpenes, 5 sesquiterpenes and 15 were not terpenes. Sesquiterpenes were the main terpenes emitted from T. tinctoria. Total VOC emission rates were on average about 15 times higher in summer than in early spring. The maximum rates of emission were recorded around midday. Emissions nearly stopped in the dark. No significant differences were found for nocturnal total terpene emission rates between places and seasons. The seasonal variations in the rate of terpene emissions and in their chemical composition can be explained mainly by dramatic changes in emission factors (emission capacity) associated in some cases, such as for beech trees, with very different foliar ontogenical characteristics between spring and summer. The results show that temperature and light-standardised emission rates were on average about 15 times higher in summer than in early spring, which, corroborating other works, calls to attention when applying the same emission factor in modelling throughout the different seasons of the year.

  5. Effect of intraspecific competition and substrate type on terpene emissions from some Mediterranean plant species.

    Science.gov (United States)

    Ormeño, Elena; Bousquet-Mélou, Anne; Mévy, Jean-Philippe; Greff, Stéphane; Robles, Christine; Bonin, Gilles; Fernandez, Catherine

    2007-02-01

    Competition is an important factor that has been extensively reported in the Mediterranean area. There is evidence that leaf terpene accumulation may vary between plants growing on calcareous and siliceous soils. In the present study, leaf terpene emissions from potted seedlings of Pinus halepensis, Cistus albidus, and Quercus coccifera, growing under natural environmental conditions on calcareous and siliceous substrates, were studied by using a bag enclosure method. In both substrates, seedlings were potted alone and in intraspecific competition, to examine the effect of substrate type and that of intraspecific competition on terpene emissions. The results showed that competition favored: (i) overall monoterpene and sesquiterpene emissions from Q. coccifera; (ii) overall monoterpene emissions from P. halepensis; (iii) overall sesquiterpene emissions from C. albidus. Substrate type affected terpene emissions to a limited extent and in a species-specific way. Whereas for Q. coccifera, the overall monoterpene emissions and that of Allo-aromadendrene were favored on siliceous substrate, no significant changes were found in emissions from P. halepensis. Only the release of AR-curcumene from C. albidus was higher on siliceous substrate. We also found high variability in terpene emission composition from the study species, particularly for P. halepensis and Q. coccifera. These two species released both monoterpenes and sesquiterpenes, instead of monoterpenes only, as shown in previous studies.

  6. Identification of amino acid networks governing catalysis in the closed complex of class I terpene synthases.

    Science.gov (United States)

    Schrepfer, Patrick; Buettner, Alexander; Goerner, Christian; Hertel, Michael; van Rijn, Jeaphianne; Wallrapp, Frank; Eisenreich, Wolfgang; Sieber, Volker; Kourist, Robert; Brück, Thomas

    2016-02-23

    Class I terpene synthases generate the structural core of bioactive terpenoids. Deciphering structure-function relationships in the reactive closed complex and targeted engineering is hampered by highly dynamic carbocation rearrangements during catalysis. Available crystal structures, however, represent the open, catalytically inactive form or harbor nonproductive substrate analogs. Here, we present a catalytically relevant, closed conformation of taxadiene synthase (TXS), the model class I terpene synthase, which simulates the initial catalytic time point. In silico modeling of subsequent catalytic steps allowed unprecedented insights into the dynamic reaction cascades and promiscuity mechanisms of class I terpene synthases. This generally applicable methodology enables the active-site localization of carbocations and demonstrates the presence of an active-site base motif and its dominating role during catalysis. It additionally allowed in silico-designed targeted protein engineering that unlocked the path to alternate monocyclic and bicyclic synthons representing the basis of a myriad of bioactive terpenoids.

  7. Radical behaviorism and scientific frameworks. From mechanistic to relational accounts.

    Science.gov (United States)

    Chiesa, M

    1992-11-01

    A substantial portion of B. F. Skinner's scholarship was devoted to developing methods and terms for a scientific study of behavior. Three concepts central to scientific accounts--cause, explanation, and theory--are examined to illustrate the distinction between mechanistic and relational frameworks and radical behaviorism's relationship to those frameworks. Informed by a scientific tradition that explicitly rejects mechanistic interpretations, radical behaviorism provides a distinctive stance in contemporary psychology. The present analysis suggests that radical behaviorism makes closer contact with the "new world view" advocated by physicists and philosophers of science than does much of contemporary psychology.

  8. Molecular architecture and biomedical leads of terpenes from red sea marine invertebrates.

    Science.gov (United States)

    Hegazy, Mohamed Elamir F; Mohamed, Tarik A; Alhammady, Montaser A; Shaheen, Alaa M; Reda, Eman H; Elshamy, Abdelsamed I; Aziz, Mina; Paré, Paul W

    2015-05-20

    Marine invertebrates including sponges, soft coral, tunicates, mollusks and bryozoan have proved to be a prolific source of bioactive natural products. Among marine-derived metabolites, terpenoids have provided a vast array of molecular architectures. These isoprenoid-derived metabolites also exhibit highly specialized biological activities ranging from nerve regeneration to blood-sugar regulation. As a result, intense research activity has been devoted to characterizing invertebrate terpenes from both a chemical and biological standpoint. This review focuses on the chemistry and biology of terpene metabolites isolated from the Red Sea ecosystem, a unique marine biome with one of the highest levels of biodiversity and specifically rich in invertebrate species.

  9. Molecular Architecture and Biomedical Leads of Terpenes from Red Sea Marine Invertebrates

    Directory of Open Access Journals (Sweden)

    Mohamed Elamir F. Hegazy

    2015-05-01

    Full Text Available Marine invertebrates including sponges, soft coral, tunicates, mollusks and bryozoan have proved to be a prolific source of bioactive natural products. Among marine-derived metabolites, terpenoids have provided a vast array of molecular architectures. These isoprenoid-derived metabolites also exhibit highly specialized biological activities ranging from nerve regeneration to blood-sugar regulation. As a result, intense research activity has been devoted to characterizing invertebrate terpenes from both a chemical and biological standpoint. This review focuses on the chemistry and biology of terpene metabolites isolated from the Red Sea ecosystem, a unique marine biome with one of the highest levels of biodiversity and specifically rich in invertebrate species.

  10. The α-terpineol to 1,8-cineole cyclization reaction of tobacco terpene synthases

    NARCIS (Netherlands)

    Piechulla, Birgit; Bartelt, Richard; Brosemann, Anne; Effmert, Uta; Bouwmeester, Harro; Hippauf, Frank; Brandt, Wolfgang

    2016-01-01

    Flowers of Nicotiana species emit a characteristic blend including the cineole cassette monoterpenes. This set of terpenes is synthesized by multiproduct enzymes, with either 1,8-cineole or α-terpineol contributing most to the volatile spectrum, thus referring to cineole or terpineol synthase,

  11. Separation of attogram terpenes by the capillary zone electrophoresis with fluorometric detection

    Czech Academy of Sciences Publication Activity Database

    Kubesová, Anna; Horká, Marie; Růžička, F.; Šlais, Karel; Glatz, Z.

    2010-01-01

    Roč. 1217, č. 46 (2010), s. 7288-7292 ISSN 0021-9673 R&D Projects: GA AV ČR IAAX00310701 Institutional research plan: CEZ:AV0Z40310501 Keywords : terpenes * farnesol * Candida albicans Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 4.194, year: 2010

  12. 75 FR 39450 - Terpene Constituents of the Extract of Chenopodium ambrosioides

    Science.gov (United States)

    2010-07-09

    ....'' This includes exposure through drinking water and in residential settings, but does not include... pesticides. Second, EPA examines exposure to the pesticide through food, drinking water, and through other... consumption. 2. d-Limonene is a major terpene constituent of lemon oil, orange oil, and grapefruit oil; a...

  13. Ozone-initiated terpene reaction products in five European offices: Replacement of a floor cleaning agent

    NARCIS (Netherlands)

    Nørgaard, A.W.; Kofoed-Sørensen, V.; Mandin, C.; Ventura, G.; Mabilia, R.; Perreca, E.; Cattaneo, A.; Spinazzè, A.; Mihucz, V.G.; Szigeti, T.; De Kluizenaar, Y.; Cornelissen, H.J.M.; Trantallidi, M.; Carrer, P.; Sakellaris, I.; Bartzis, J.; Wolkoff, P.

    2014-01-01

    Cleaning agents often emit terpenes that react rapidly with ozone. These ozone-initiated reactions, which occur in the gas-phase and on surfaces, produce a host of gaseous and particulate oxygenated compounds with possible adverse health effects in the eyes and airways. Within the European Union

  14. Compartmentation of mono- and sesqui-terpene biosynthesis of the essential oil in poncirus trifoliata

    International Nuclear Information System (INIS)

    Heinrich, G.; Wegener, R.; Schultze, W.

    1980-01-01

    The fruit of Poncirus trifoliata shows glandular cells complexes in the exocarp, which produce a volatile oil rich in monoterpenes but poor in sesquiterpenes and oxigenated compounds. The juice vesicles of the endocarp possess similar cell complexes mainly containing sesquiterpenes and oxigenated compounds, whereas monoterpenes only occur in small amounts. By the use of combined gas chromatography-mass spectrometry 19 components of the rind oil and 15 compounds of the endocarp oil could be identified. As demonstrated by electron microscopy the terpenes most probably are synthesized predominantly, if not exclusively in plastids. As shown by gasradiochromatography radioactive precursors ( 14 Co 2 and 14 C-leucine) are incorporated into mono- and sesqui-terpenes to a different extent. This is due to two gland types producing essential oils of different composition with regard to their mono- and sesqui-terpene percentage. In fruit development the exocarp glands differentiate earlier than the endocarp glands do. The activity of exogenously applied 14 Co 2 first reaches the peripheral glands and later on appears in the interior glands. Depending upon the growth season, labelled leucine transported by the conducting tissues from lower plant parts leads to a high specific activity of the sesqui-terpenes and oxigenated compounds. It could be argued that in this instance the glands of the pulp are better provided with precursors than the exocarp glands. The successive maxima of essential oil production in both glandular complexes, and the changes in the concentration of individual oil constituents during the ontogeny of the fruit also contribute to different incorporation ratios of radioactive precursors into mono- and sesqui-terpenes. (author)

  15. CCN activity of secondary aerosols from terpene ozonolysis under atmospheric relevant conditions

    Science.gov (United States)

    Yuan, Cheng; Ma, Yan; Diao, Yiwei; Yao, Lei; Zhou, Yaoyao; Wang, Xing; Zheng, Jun

    2017-04-01

    Gas-phase ozonolysis of terpenes is an important source of atmospheric secondary organic aerosol. The contribution of terpene-derived aerosols to the atmospheric cloud condensation nucleus (CCN) burden under atmospheric conditions, however, remains highly uncertain. The results obtained in previous studies under simple laboratory conditions may not be applicable to atmospheric relevant conditions. Here we present that CCN activities of aerosols from terpene ozonolysis can be significantly affected by atmospheric relevant species that can act as stabilized Criegee intermediate (SCI) or OH scavengers. Ozonolysis reactions of α-pinene, limonene, α-cedrene, and α-humulene were conducted in a 4.5 m3 collapsible fluoropolymer chamber at near-atmospheric concentrations in the presence of different OH scavengers (cyclohexane, 2-butanol, or CO) and SCI scavengers (CH3COOH, H2O, or SO2). The number size distribution and CCN activity of aerosol particles formed during ozonolysis were simultaneously determined. Additionally, particulate products were chemically analyzed by using a Filter Inlet for Gases and AEROsols High-Resolution Time-of-Flight Chemical-Ionization Mass Spectrometer. Results showed that aerosol CCN activity following monoterpene ozonolysis was more sensitive to the choice of OH scavengers, while that from sesquiterpene ozonolysis was significantly affected by SCI scavengers. Combined with chemical analysis results, it was concluded that the unimolecular decomposition of CIs giving hygroscopic organic products can be largely suppressed by bimolecular reactions during sesquiterpene ozonolysis but was not significantly impacted in monoterpene ozonolysis. Our study underscores the key role of CIs in the CCN activity of terpene ozonolysis-derived aerosols. The effects of atmospheric relevant species (e.g., SO2, H2O, and CO) need to be considered when assessing the contribution of biogenic terpenes to the atmospheric CCN burden under ambient conditions.

  16. The health significance of gas- and particle-phase terpene oxidation products: a review.

    Science.gov (United States)

    Rohr, Annette C

    2013-10-01

    The reactions between terpenes and ozone (or other oxidants) produce a wide variety of both gas- and particle-phase products. Terpenes are biogenic volatile organic compounds (VOCs) that are also contained in many consumer products. Ozone is present indoors since it infiltrates into the indoor environment and is emitted by some office and consumer equipment. Some of the gaseous products formed are irritating to biological tissues, while the condensed-phase products have received attention due to their contribution to ambient fine particulate matter (PM2.5) and its respective health significance. Despite common scientific questions, the indoor and ambient air research communities have tended to operate in isolation regarding this topic. This review critically evaluates the literature related to terpene oxidation products and attempts to synthesize results of indoor and ambient air studies to better understand the health significance of these materials and identify knowledge gaps. The review documents the results of a literature search covering terpene oxidation chemistry, epidemiological, toxicological, and controlled human exposure studies, as well as health studies focused more generically on secondary organic aerosol (SOA). The literature shows a clear role for gas-phase terpene oxidation products in adverse airway effects at high concentrations; however, whether these effects occur at more environmentally relevant levels is unclear. The evidence for toxicity of particle-phase products is less conclusive. Knowledge gaps and future research needs are outlined, and include the need for more consistency in study designs, incorporation of reaction product measurements into epidemiological studies conducted in both indoor and ambient settings, and more focused research on the toxicity of SOA, especially SOA of biogenic origin. © 2013.

  17. Characterization of CYP264B1 and a terpene cyclase of a terpene biosynthesis gene cluster from the myxobacterium Sorangium cellulosum So ce56

    OpenAIRE

    Ly, Thuy Thi Bich

    2011-01-01

    In the work presented here, CYP264B1 and the terpene cyclase GeoA of Sorangium cellulosum So ce56 have been characterized. CYP264B1 is able to convert norisoprenoids (a-ionone and b-ionone) and diverse sesquiterpene compounds, including nootkatone. Three products, 3-hydroxy-a-ionone, 3-hydroxy-b-ionone and 13-hydroxy-nootkatone were characterized using HPLC and 1H and 13C NMR. CYP264B1 is the first enzyme reported to be capable to hydroxylate regioselectively both norisoprenoids at the positi...

  18. Analysis of terpene lactones in a Ginkgo leaf extract by high-performance liquid chromatography using charged aerosol detection.

    Science.gov (United States)

    Kakigi, Yasuhiro; Mochizuki, Naoki; Icho, Takeshi; Hakamatsuka, Takashi; Goda, Yukihiro

    2010-01-01

    A new HPLC method using charged aerosol detection was developed for the determination of terpene lactones in a Ginkgo leaf extract. The linearity of the standard curves was excellent (r>0.999). The repeatability of the method was less than 3%, and its reproducibility was less than 5% for each analyte. The limit of detection was between 0.087 and 0.45 microg/ml. The developed method was applied to the analysis of terpene lactones in Ginkgo leaf products distributed in the Japanese market. The results suggest that some health food products contained approximately equivalent amounts of terpene lactones to those in the medical product and that the proportion of terpene lactones varied in each health product.

  19. Frankincense derived heavy terpene cocktail boosting breast cancer cell (MDA-MB-231 death in vitro

    Directory of Open Access Journals (Sweden)

    Faruck Lukmanul Hakkim

    2015-10-01

    Conclusions: Extracting anti-cancer active principle cocktail by simple Soxhlet method is cost effective and less time consuming. Our in vitro anti-cancer data forms the rationale for us to test heavy terpene complex in breast cancer xenograft model in vivo. Furthermore, fractionation and developing frankincense heavy terpene based breast cancer drug is the major goal of our laboratory.

  20. A maize landrace that emits defense volatiles in response to?herbivore eggs possesses a strongly inducible terpene synthase gene

    OpenAIRE

    Tamiru, Amanuel; Bruce, Toby J. A.; Richter, Annett; Woodcock, Christine M.; Midega, Charles A. O.; Degenhardt, J?rg; Kelemu, Segenet; Pickett, John A.; Khan, Zeyaur R.

    2017-01-01

    Maize (Zea mays) emits volatile terpenes in response to insect feeding and egg deposition\\ud to defend itself against harmful pests. However, maize cultivars differ strongly in\\ud their ability to produce the defense signal. To further understand the agroecological\\ud role and underlying genetic mechanisms for variation in terpene emission among\\ud maize cultivars, we studied the production of an important signaling component (E)-caryophyllene\\ud in a South American maize landrace Braz1006 po...

  1. Allylic chlorination of terpenic olefins using a combination of MoCl{sub 5} and NaOCl

    Energy Technology Data Exchange (ETDEWEB)

    Boualy, Brahim; Firdoussi, Larbi El; Ali, Mustapha Ait; Karim, Abdellah, E-mail: elfirdoussi@ucam.ac.m [Universite Cadi Ayyad, Marrakech (Morocco). Faculte des Sciences Semlalia. Lab. de Chimie de Coordination

    2011-07-01

    MoCl{sub 5} is applied as efficient agent in allylic chlorination of terpenic olefins in the presence of NaOCl as chlorine donor. Various terpenes are converted to the corresponding allylic chlorides in moderate to good yield under mild and optimized reaction conditions. Different molybdenum precursors are also studied. Among them, MoO{sub 3} gives good yield, but after a longer reaction time. (author)

  2. Fungal endophytes – the hidden inducers of volatile terpene biosynthesis in tomato plants

    DEFF Research Database (Denmark)

    Ntana, Fani; Jensen, Birgit; Jørgensen, Hans Jørgen Lyngs

    and herbivores. Tomato (Solanum lycopersicum) is an important crop, often challenged by fungal pathogens and insect pests. The wide variety of secondary metabolites produced by the plant, and especially terpenes, play a crucial role in plant defence, helping in repelling possible enemies. This project is focused...... on establishing a balanced interaction between S. indica and tomato in vitro, as well as reliable detection methods that show fungal colonization of inoculated plant roots. The effect of root colonization by S. indica on host specialized metabolism is also determined, by comparing volatile terpene profiles of S......Endophytes comprise a polyphyletic and diverse group of microorganisms that colonize plant tissues and do not cause any immediate infection symptoms. Revealing the mechanisms of plant-endophyte mutualistic interactions has attracted considerable attention lately, mainly due to their multiple...

  3. HPLC determination of certain flavonoids and terpene lactones in selected Ginkgo biloba L. phytopharmaceuticals.

    Science.gov (United States)

    Mesbah, Mostafa K; Khalifa, Sherief I; El-Gindy, Alaa; Tawfik, Kamilia A

    2005-01-01

    The biologically active secondary metabolites of Ginkgo biloba extract EGb 761 in phytopharmaceuticals were analyzed using two simple, rapid, accurate and sensitive HPLC methods. The proposed methods were successfully applied in the determination of terpenes and flavonoids in four phytopharmaceutical preparations selected from the Egyptian market. The terpenes; ginkgolide A, ginkgolide B, and bilobalide were analyzed using RP 18 column with a mobile phase consisting of water/methanol/isopropanol (72.5:17.5:10, v/v) at a flow rate of 1 ml min-1 and UV detection at 220 nm. The flavonoids; quercetin and kaempferol were analyzed using RP 18 column in a step gradient elution with acetonitrile and water at pH 3.3 and flow rate of 1.5 ml min-1 with UV detection at 370 nm. The two HPLC methods were completely validated.

  4. [Regulation of terpene metabolism]. Annual progress report, March 15, 1989--March 14, 1990

    Energy Technology Data Exchange (ETDEWEB)

    Croteau, R.

    1989-11-09

    Terpenoid oils, resins, and waxes from plants are important renewable resources. The objective of this project is to understand the regulation of terpenoid metabolism using the monoterpenes (C{sub 10}) as a model. The pathways of monoterpene biosynthesis and catabolism have been established, and the relevant enzymes characterized. Developmental studies relating enzyme levels to terpene accumulation within the oil gland sites of synthesis, and work with bioregulators, indicate that monoterpene production is controlled by terpene cyclases, the enzymes catalyzing the first step of the monoterpene pathway. As the leaf oil glands mature, cyclase levels decline and monoterpene biosynthesis ceases. Yield then decreases as the monoterpenes undergo catabolism by a process involving conversion to a glycoside and transport from the leaf glands to the root. At this site, the terpenoid is oxidatively degraded to acetate that is recycled into other lipid metabolites. During the transition from terpene biosynthesis to catabolism, the oil glands undergo dramatic ultrastructural modification. Degradation of the producing cells results in mixing of previously compartmentized monoterpenes with the catabolic enzymes, ultimately leading to yield decline. This regulatory model is being applied to the formation of other terpenoid classes (C{sub 15} C{sub 20}, C{sub 30}, C{sub 40}) within the oil glands. Preliminary investigations on the formation of sesquiterpenes (C{sub 15}) suggest that the corresponding cyclases may play a lesser role in determining yield of these products, but that compartmentation effects are important. From these studies, a comprehensive scheme for the regulation of terpene metabolism is being constructed. Results from this project wail have important consequences for the yield and composition of terpenoid natural products that can be made available for industrial exploitation.

  5. Selected terpenes from leaves of Ocimum basilicum L. induce hemoglobin accumulation in human K562 cells.

    Science.gov (United States)

    Giordana, Feriotto; Nicola, Marchetti; Valentina, Costa; Torricelli, Piera; Beninati, Simone; Tagliati, Federico; Mischiati, Carlo

    2018-02-13

    Re-expression of fetal hemoglobin (HbF) was proposed as a possible therapeutic strategy for β-haemoglobinopathies. Although several inducers of HbF were tested in clinical trials, only hydroxyurea (HU) received FDA approval. Despite it produced adequate HbF levels only in half of HU-treated SCD patients, and was ineffective at all in β-thalassemia patients, beneficial effects of this approach suggested to continue in this direction identifying further molecules capable of inducing HbF. We tested the potential of essential oil isolated from Ocimum basilicum L. leaves (ObEO) in inducing hemoglobin biosynthesis. Initially, dose-dependent effect and kinetics of hemoglobin accumulation in K562 cells after treatment with ObEO were evaluated. ObEO induced dose-dependent hemoglobin accumulation superior to hydroxyurea and rapamycin and a strongest γ-globin mRNA expression. Terpenes composition of ObEO was studied by GC-MS. Three main constituents, linalool, eugenol and eucalyptol, represented about 75% of total. A blend of these three terpenes fully replicated the ObEO's biological effect, thus indicating that one of them or all together could be the active ingredients. When terpenes were tested individually, eugenol was the only one inducing stable hemoglobin accumulation, while eucalyptol and linalool produced only a small transient response. However, eugenol potential was strongly enhanced in the presence of eucalyptol and linalool, suggesting a synergistic effect on hemoglobin accumulation. By these results, the discovery of a new inducer and the interesting activity of a blend of major terpenes from ObOE on Hb accumulation could have positive fallouts on β-thalassemia and sickle cells anemia. Copyright © 2018 Elsevier B.V. All rights reserved.

  6. Induction of Terpene Biosynthesis in Berries of Microvine Transformed with VvDXS1 Alleles

    OpenAIRE

    Dalla Costa, Lorenza; Emanuelli, Francesco; Trenti, Massimiliano; Moreno-Sanz, Paula; Lorenzi, Silvia; Coller, Emanuela; Moser, Sergio; Slaghenaufi, Davide; Cestaro, Alessandro; Larcher, Roberto; Gribaudo, Ivana; Costantini, Laura; Malnoy, Mickael; Grando, M. Stella

    2018-01-01

    Terpenoids, especially monoterpenes, are major aroma-impact compounds in grape and wine. Previous studies highlighted a key regulatory role for grapevine 1-deoxy-D-xylulose 5-phosphate synthase 1 (VvDXS1), the first enzyme of the methylerythritol phosphate pathway for isoprenoid precursor biosynthesis. Here, the parallel analysis of VvDXS1 genotype and terpene concentration in a germplasm collection demonstrated that VvDXS1 sequence has a very high predictive value for the accumulation of mon...

  7. Relative expression of genes of terpene metabolism in different tissues of Artemisia annua L

    OpenAIRE

    Olofsson, Linda; Engström, Alexander; Lundgren, Anneli; Brodelius, Peter E

    2011-01-01

    Abstract Background Recently, Artemisia annua L. (annual or sweet wormwood) has received increasing attention due to the fact that the plant produces the sesquiterpenoid endoperoxide artemisinin, which today is widely used for treatment of malaria. The plant produces relatively small amounts of artemisinin and a worldwide shortage of the drug has led to intense research in order to increase the yield of artemisinin. In order to improve our understanding of terpene metabolism in the plant and ...

  8. Crystal Structure of Albaflavenone Monooxygenase Containing a Moonlighting Terpene Synthase Active Site

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Bin; Lei, Li; Vassylyev, Dmitry G.; Lin, Xin; Cane, David E.; Kelly, Steven L.; Yuan, Hang; Lamb, David C.; Waterman, Michael R.; (Vanderbilt); (UAB); (Brown); (Swansea)

    2010-01-08

    Albaflavenone synthase (CYP170A1) is a monooxygenase catalyzing the final two steps in the biosynthesis of this antibiotic in the soil bacterium, Streptomyces coelicolor A3(2). Interestingly, CYP170A1 shows no stereo selection forming equal amounts of two albaflavenol epimers, each of which is oxidized in turn to albaflavenone. To explore the structural basis of the reaction mechanism, we have studied the crystal structures of both ligand-free CYP170A1 (2.6 {angstrom}) and complex of endogenous substrate (epi-isozizaene) with CYP170A1 (3.3 {angstrom}). The structure of the complex suggests that the proximal epi-isozizaene molecules may bind to the heme iron in two orientations. In addition, much to our surprise, we have found that albaflavenone synthase also has a second, completely distinct catalytic activity corresponding to the synthesis of farnesene isomers from farnesyl diphosphate. Within the cytochrome P450 {alpha}-helical domain both the primary sequence and x-ray structure indicate the presence of a novel terpene synthase active site that is moonlighting on the P450 structure. This includes signature sequences for divalent cation binding and an {alpha}-helical barrel. This barrel is unusual because it consists of only four helices rather than six found in all other terpene synthases. Mutagenesis establishes that this barrel is essential for the terpene synthase activity of CYP170A1 but not for the monooxygenase activity. This is the first bifunctional P450 discovered to have another active site moonlighting on it and the first time a terpene synthase active site is found moonlighting on another protein.

  9. Design of countercurrent separation of Ginkgo biloba terpene lactones by nuclear magnetic resonance.

    Science.gov (United States)

    Qiu, Feng; Friesen, J Brent; McAlpine, James B; Pauli, Guido F

    2012-06-15

    Terpene lactones such as bilobalide, ginkgolides A, B, C, and J are major bioactive compounds of Ginkgo biloba L. Purification of these compounds is tedious due to their similar chemical properties. For the purpose of developing an effective and efficient method for both analytical and preparative separation of terpene lactones in G. biloba, an innovative orthogonality-enhanced high-speed countercurrent chromatography (HSCCC) method was established. Taking advantage of quantitative (1)H NMR (qHNMR) methodology, partition coefficients (K) of individual terpene lactones were calculated directly from crude G. biloba leaf extract, using their H-12 signals as distinguishing feature. The partitioning experiment assisted the design of a two dimensional (2D) HSCCC procedure using a pair of orthogonal HSCCC solvent systems (SSs), ChMWat +4 and HEMSoWat +3/0.05%. It was surprising that the resolution of ginkgolides A and B was improved by 25% in the HEMWat +3 SS modified with 0.5% DMSO. Consequently, all five terpene lactones could be well separated with qHNMR purity>95% from G. biloba leaf extract. The separation was further evaluated by offline qHNMR analysis of HSCCC fractions associated with Gaussian curve fitting. The results showed less than 2% error in HSCCC retention predicted from the partitioning experiment. This compelling consistency demonstrates that qHNMR-derived K determination ("K-by-NMR") can be used to predict CCC fractionation and target purification of analytes from complex mixtures. Furthermore, Gaussian curve fitting enabled an accurate prediction of less than 2% impurity in the CCC fraction, which demonstrates its potential as a powerful tool to study the presence of minor constituents, especially when they are beyond the detection limit of conventional spectroscopic detectors. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. CYP109E1 is a novel versatile statin and terpene oxidase from Bacillus megaterium.

    Science.gov (United States)

    Putkaradze, Natalia; Litzenburger, Martin; Abdulmughni, Ammar; Milhim, Mohammed; Brill, Elisa; Hannemann, Frank; Bernhardt, Rita

    2017-12-01

    CYP109E1 is a cytochrome P450 monooxygenase from Bacillus megaterium with a hydroxylation activity for testosterone and vitamin D3. This study reports the screening of a focused library of statins, terpene-derived and steroidal compounds to explore the substrate spectrum of this enzyme. Catalytic activity of CYP109E1 towards the statin drug-precursor compactin and the prodrugs lovastatin and simvastatin as well as biotechnologically relevant terpene compounds including ionones, nootkatone, isolongifolen-9-one, damascones, and β-damascenone was found in vitro. The novel substrates induced a type I spin-shift upon binding to P450 and thus permitted to determine dissociation constants. For the identification of conversion products by NMR spectroscopy, a B. megaterium whole-cell system was applied. NMR analysis revealed for the first time the ability of CYP109E1 to catalyze an industrially highly important reaction, the production of pravastatin from compactin, as well as regioselective oxidations generating drug metabolites (6'β-hydroxy-lovastatin, 3'α-hydroxy-simvastatin, and 4″-hydroxy-simvastatin) and valuable terpene derivatives (3-hydroxy-α-ionone, 4-hydroxy-β-ionone, 11,12-epoxy-nootkatone, 4(R)-hydroxy-isolongifolen-9-one, 3-hydroxy-α-damascone, 4-hydroxy-β-damascone, and 3,4-epoxy-β-damascone). Besides that, a novel compound, 2-hydroxy-β-damascenone, produced by CYP109E1 was identified. Docking calculations using the crystal structure of CYP109E1 rationalized the experimentally observed regioselective hydroxylation and identified important amino acid residues for statin and terpene binding.

  11. Suites of terpene synthases explain differential terpenoid production in ginger and turmeric tissues.

    Directory of Open Access Journals (Sweden)

    Hyun Jo Koo

    Full Text Available The essential oils of ginger (Zingiber officinale and turmeric (Curcuma longa contain a large variety of terpenoids, some of which possess anticancer, antiulcer, and antioxidant properties. Despite their importance, only four terpene synthases have been identified from the Zingiberaceae family: (+-germacrene D synthase and (S-β-bisabolene synthase from ginger rhizome, and α-humulene synthase and β-eudesmol synthase from shampoo ginger (Zingiber zerumbet rhizome. We report the identification of 25 mono- and 18 sesquiterpene synthases from ginger and turmeric, with 13 and 11, respectively, being functionally characterized. Novel terpene synthases, (--caryolan-1-ol synthase and α-zingiberene/β-sesquiphellandrene synthase, which is responsible for formation of the major sesquiterpenoids in ginger and turmeric rhizomes, were also discovered. These suites of enzymes are responsible for formation of the majority of the terpenoids present in these two plants. Structures of several were modeled, and a comparison of sets of paralogs suggests how the terpene synthases in ginger and turmeric evolved. The most abundant and most important sesquiterpenoids in turmeric rhizomes, (+-α-turmerone and (+-β-turmerone, are produced from (--α-zingiberene and (--β-sesquiphellandrene, respectively, via α-zingiberene/β-sesquiphellandrene oxidase and a still unidentified dehydrogenase.

  12. Suites of Terpene Synthases Explain Differential Terpenoid Production in Ginger and Turmeric Tissues

    Science.gov (United States)

    Koo, Hyun Jo; Gang, David R.

    2012-01-01

    The essential oils of ginger (Zingiber officinale) and turmeric (Curcuma longa) contain a large variety of terpenoids, some of which possess anticancer, antiulcer, and antioxidant properties. Despite their importance, only four terpene synthases have been identified from the Zingiberaceae family: (+)-germacrene D synthase and (S)-β-bisabolene synthase from ginger rhizome, and α-humulene synthase and β-eudesmol synthase from shampoo ginger (Zingiber zerumbet) rhizome. We report the identification of 25 mono- and 18 sesquiterpene synthases from ginger and turmeric, with 13 and 11, respectively, being functionally characterized. Novel terpene synthases, (−)-caryolan-1-ol synthase and α-zingiberene/β-sesquiphellandrene synthase, which is responsible for formation of the major sesquiterpenoids in ginger and turmeric rhizomes, were also discovered. These suites of enzymes are responsible for formation of the majority of the terpenoids present in these two plants. Structures of several were modeled, and a comparison of sets of paralogs suggests how the terpene synthases in ginger and turmeric evolved. The most abundant and most important sesquiterpenoids in turmeric rhizomes, (+)-α-turmerone and (+)-β-turmerone, are produced from (−)-α-zingiberene and (−)-β-sesquiphellandrene, respectively, via α-zingiberene/β-sesquiphellandrene oxidase and a still unidentified dehydrogenase. PMID:23272109

  13. Synthesis and antibacterial properties of 2,3-dideoxyglucosides of terpene alcohols and phenols.

    Science.gov (United States)

    Bound, D James; Murthy, Pushpa S; Srinivas, P

    2015-10-15

    Essential oils and their oxygenated terpene constituents possess potent antimicrobial properties. In the present study, a facile synthetic route to the 2,3-dideoxy 1-O-glucosides of important phenols and terpene alcohols in excellent yields (85-96%) has been delineated. Studies on their antimicrobial action against four food-borne pathogens--Bacillus cereus, Staphylococcus aureus, Escherichia coli and Yersinia enterocolitica--demonstrated that the zone of inhibition, in general, was higher for the 2,3-unsaturated 1-O-glucoside derivatives (1b-6b) and the corresponding saturated glucosides (1c-5c) when compared to the parent alcohols/phenols (1-6). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values for these derivatives too were generally lower than those of the parent compounds. Furthermore, the time-kill and bacteriolysis assays too demonstrated the greater antimicrobial potential of the derivatives. The 2,3-dideoxy 1-O-glucosides of phenols and terpene alcohols were more effective in their antimicrobial action than the corresponding parent compounds. The study indicated that these novel derivatives can find useful application in control of food-related pathogenic microbes in foods. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Insights into molecular architecture of terpenes using small angle neutron scattering

    Science.gov (United States)

    Rai, Durgesh K.; Annamraju, Aparna; Pingali, Sai Venkatesh; O'Neill, Hugh M.; Mewalal, Ritesh; Gunter, Lee E.; Tuskan, Gerald A.

    Understanding macromolecular architectures is vital to engineering prospective terpene candidates for advanced biofuels. Eucalyptus plants store terpenes in specialized cavity-like structures in the leaves called oil glands, which comprises of volatile (VTs) and non-volatile (NVTs) terpenes. Using small-angle neutron scattering, we have investigated the structure and phase behavior of the supramolecular assembly formed by Geranyl beta-D-glucoside (GDG), a NVT and compare the results with that of beta-octyl glucoside (BOG). The formation of micellar structures was observed in the concentration range of 0.5-5 v/v% in water using small angle neutron scattering (SANS) where Schultz sphere model was used in quantifying structural parameters of micelles. SANS studies determine that GDG and BOG behave like amphiphiles forming micellar structures in aqueous solution. The micelles swell upon addition of alpha-Pinene (AP) indicating partition to the core region of the micelles. The general behavior of the micellar growth after partitioning of AP to form thermodynamically stable sizes varies with the NVT concentration. Our studies reveal that the presence of steric hindrance in the GDG via the unsaturated bonds could help stabilize VTs inside the oil glands. LDRD project LOIS ID 7428, SNS, CSMB, HFIR, ORNL, DOE Office of Science User Facilities.

  15. Food for Thought ... Mechanistic Validation

    Science.gov (United States)

    Hartung, Thomas; Hoffmann, Sebastian; Stephens, Martin

    2013-01-01

    Summary Validation of new approaches in regulatory toxicology is commonly defined as the independent assessment of the reproducibility and relevance (the scientific basis and predictive capacity) of a test for a particular purpose. In large ring trials, the emphasis to date has been mainly on reproducibility and predictive capacity (comparison to the traditional test) with less attention given to the scientific or mechanistic basis. Assessing predictive capacity is difficult for novel approaches (which are based on mechanism), such as pathways of toxicity or the complex networks within the organism (systems toxicology). This is highly relevant for implementing Toxicology for the 21st Century, either by high-throughput testing in the ToxCast/ Tox21 project or omics-based testing in the Human Toxome Project. This article explores the mostly neglected assessment of a test's scientific basis, which moves mechanism and causality to the foreground when validating/qualifying tests. Such mechanistic validation faces the problem of establishing causality in complex systems. However, pragmatic adaptations of the Bradford Hill criteria, as well as bioinformatic tools, are emerging. As critical infrastructures of the organism are perturbed by a toxic mechanism we argue that by focusing on the target of toxicity and its vulnerability, in addition to the way it is perturbed, we can anchor the identification of the mechanism and its verification. PMID:23665802

  16. Stability assessment of gas mixtures containing terpenes at nominal 5 nmol/mol contained in treated aluminum gas cylinders.

    Science.gov (United States)

    Rhoderick, George C

    2010-10-01

    Studies of climate change increasingly recognize the diverse influences exerted by terpenes in the atmosphere, including roles in particulates, ozone formation, and their oxidizing potential. Measurements of key terpenes suggest atmospheric concentrations ranging from low pmol/mol (parts per trillion) to nmol/mol (parts per billion), depending on location and compound. To accurately establish concentration trends, assess the role of terpenes in atmospheric chemistry, and relate measurement records from many laboratories and researchers, it is essential to have good calibration standards. The feasibility of preparing well-characterized, stable gas cylinder standards for terpenes at the nmol/mol level is not yet well established. Several of the world's National Metrology Institutes (NMIs) are researching the feasibility of developing primary and secondary reference gas standards at the nmol/mol level for terpenes. The US NMI, the National Institute of Standards and Technology, has prepared several nmol/mol mixtures, in treated aluminum gas cylinders, containing terpenes in dry nitrogen at nominal 5 nmol/mol for stability studies. Overall, 11 terpenes were studied for stability. An initial gas mixture containing nine terpenes, one oxygenate, and six aromatic compounds, including benzene as an internal standard, was prepared. Results for four of the nine terpenes in this initial mixture indicate stability in these treated aluminum gas cylinders for over 6 months and project long term (years) stability. Interesting results were seen for beta-pinene, which when using a linear equation rate decline predicts that it will reach a zero concentration level at day 416. At the same time, increases in alpha-pinene, D: -limonene (R-(+)-limonene), and p-cymene were observed, including camphene, a terpene not prepared in the gas mixture, indicating a chemical transformation of beta-pinene to these species. Additional mixtures containing combination of either alpha-pinene, camphor

  17. HTGR Mechanistic Source Terms White Paper

    Energy Technology Data Exchange (ETDEWEB)

    Wayne Moe

    2010-07-01

    The primary purposes of this white paper are: (1) to describe the proposed approach for developing event specific mechanistic source terms for HTGR design and licensing, (2) to describe the technology development programs required to validate the design methods used to predict these mechanistic source terms and (3) to obtain agreement from the NRC that, subject to appropriate validation through the technology development program, the approach for developing event specific mechanistic source terms is acceptable

  18. Terpenes increase the lipid dynamics in the Leishmania plasma membrane at concentrations similar to their IC50 values.

    Directory of Open Access Journals (Sweden)

    Heverton Silva Camargos

    Full Text Available Although many terpenes have shown antitumor, antibacterial, antifungal, and antiparasitic activity, the mechanism of action is not well established. Electron paramagnetic resonance (EPR spectroscopy of the spin-labeled 5-doxyl stearic acid revealed remarkable fluidity increases in the plasma membrane of terpene-treated Leishmania amazonensis promastigotes. For an antiproliferative activity assay using 5×10(6 parasites/mL, the sesquiterpene nerolidol and the monoterpenes (+-limonene, α-terpineol and 1,8-cineole inhibited the growth of the parasites with IC50 values of 0.008, 0.549, 0.678 and 4.697 mM, respectively. The IC50 values of these terpenes increased as the parasite concentration used in the cytotoxicity assay increased, and this behavior was examined using a theoretical treatment of the experimental data. Cytotoxicity tests with the same parasite concentration as in the EPR experiments revealed a correlation between the IC50 values of the terpenes and the concentrations at which they altered the membrane fluidity. In addition, the terpenes induced small amounts of cell lysis (4-9% at their respective IC50 values. For assays with high cell concentrations (2×10(9 parasites/mL, the incorporation of terpene into the cell membrane was very fast, and the IC50 values observed for 24 h and 5 min-incubation periods were not significantly different. Taken together, these results suggest that terpene cytotoxicity is associated with the attack on the plasma membrane of the parasite. The in vitro cytotoxicity of nerolidol was similar to that of miltefosine, and nerolidol has high hydrophobicity; thus, nerolidol might be used in drug delivery systems, such as lipid nanoparticles to treat leishmaniasis.

  19. Terpenes tell different tales at different scales: glimpses into the Chemical Ecology of conifer - bark beetle - microbial interactions.

    Science.gov (United States)

    Raffa, Kenneth F

    2014-01-01

    Chemical signaling mediates nearly all aspects of species interactions. Our knowledge of these signals has progressed dramatically, and now includes good characterizations of the bioactivities, modes of action, biosynthesis, and genetic programming of numerous compounds affecting a wide range of species. A major challenge now is to integrate this information so as to better understand actual selective pressures under natural conditions, make meaningful predictions about how organisms and ecosystems will respond to a changing environment, and provide useful guidance to managers who must contend with difficult trade-offs among competing socioeconomic values. One approach is to place stronger emphasis on cross-scale interactions, an understanding of which can help us better connect pattern with process, and improve our ability to make mechanistically grounded predictions over large areas and time frames. The opportunity to achieve such progress has been heightened by the rapid development of new scientific and technological tools. There are significant difficulties, however: Attempts to extend arrays of lower-scale processes into higher scale functioning can generate overly diffuse patterns. Conversely, attempts to infer process from pattern can miss critically important lower-scale drivers in systems where their biological and statistical significance is negated after critical thresholds are breached. Chemical signaling in bark beetle - conifer interactions has been explored for several decades, including by the two pioneers after whom this award is named. The strong knowledge base developed by many researchers, the importance of bark beetles in ecosystem functioning, and the socioeconomic challenges they pose, establish these insects as an ideal model for studying chemical signaling within a cross-scale context. This report describes our recent work at three levels of scale: interactions of bacteria with host plant compounds and symbiotic fungi (tree level

  20. The Contents of Terpene Trilactone and Flavonoid in Leaves of Seedlings from Ancient Female Ginkgo Trees in China

    Directory of Open Access Journals (Sweden)

    Yanhui ZHANG

    2017-07-01

    Full Text Available Flavonoids and terpene trilactones, especially, ginkgo flavonglycosides, ginkgolides and bilobalides in leaves of ginkgo trees, need to be studied for effective application of these active components with high medical and health-care values. This study was aimed to provide scientific bases for genealogies selection and harvest season confirmation for Ginkgo biloba. A high-performance liquid chromatographic method (HPLC-ELSD was developed to determine the contents of terpene trilactone and flavonoid of 36 ancient G. biloba genealogies from 19 provinces in China. The study indicated that the content gradually increased from April to August, and thereafter declined. Analysis of variance indicated that the contents of terpene trilactone, flavonoids, and their respective components had significant difference among 36 genealogies. The cluster analysis showed that No. 72 (Xing'an, Guangxi, No. 58 (Youyang, Chongqing, No. 82 (Rugao, Jiangsu, No. 123 (Huixian, Gansu, No. 99 (Dujun, Guizhou, No. 10 (Tai'an, Shandong and No. 133 (Mentougou, Beijing genealogies have higher content of terpene trilactone and flavonoid. These results can help us to select superior variety containing high content of terpene trilactone and flavonoid.

  1. Ozone-initiated terpene reaction products in five European offices: replacement of a floor cleaning agent.

    Science.gov (United States)

    Nørgaard, A W; Kofoed-Sørensen, V; Mandin, C; Ventura, G; Mabilia, R; Perreca, E; Cattaneo, A; Spinazzè, A; Mihucz, V G; Szigeti, T; de Kluizenaar, Y; Cornelissen, H J M; Trantallidi, M; Carrer, P; Sakellaris, I; Bartzis, J; Wolkoff, P

    2014-11-18

    Cleaning agents often emit terpenes that react rapidly with ozone. These ozone-initiated reactions, which occur in the gas-phase and on surfaces, produce a host of gaseous and particulate oxygenated compounds with possible adverse health effects in the eyes and airways. Within the European Union (EU) project OFFICAIR, common ozone-initiated reaction products were measured before and after the replacement of the regular floor cleaning agent with a preselected low emitting floor cleaning agent in four offices located in four EU countries. One reference office in a fifth country did not use any floor cleaning agent. Limonene, α-pinene, 3-carene, dihydromyrcenol, geraniol, linalool, and α-terpineol were targeted for measurement together with the common terpene oxidation products formaldehyde, 4-acetyl-1-methylcyclohexene (4-AMCH), 3-isopropenyl-6-oxo-heptanal (IPOH), 6-methyl-5-heptene-2-one, (6-MHO), 4-oxopentanal (4-OPA), and dihydrocarvone (DHC). Two-hour air samples on Tenax TA and DNPH cartridges were taken in the morning, noon, and in the afternoon and analyzed by thermal desorption combined with gas chromatography/mass spectrometry and HPLC/UV analysis, respectively. Ozone was measured in all sites. All the regular cleaning agents emitted terpenes, mainly limonene and linalool. After the replacement of the cleaning agent, substantially lower concentrations of limonene and formaldehyde were observed. Some of the oxidation product concentrations, in particular that of 4-OPA, were also reduced in line with limonene. Maximum 2 h averaged concentrations of formaldehyde, 4-AMCH, 6-MHO, and IPOH would not give rise to acute eye irritation-related symptoms in office workers; similarly, 6-AMCH, DHC and 4-OPA would not result in airflow limitation to the airways.

  2. Oxidized limonene and oxidized linalool - concomitant contact allergy to common fragrance terpenes

    DEFF Research Database (Denmark)

    Bråred Christensson, Johanna; Karlberg, Ann-Therese; Andersen, Klaus E

    2016-01-01

    BACKGROUND: Limonene and linalool are common fragrance terpenes. Both oxidized R-limonene and oxidized linalool have recently been patch tested in an international setting, showing contact allergy in 5.2% and 6.9% of dermatitis patients, respectively. OBJECTIVE: To investigate concomitant reactions...... of the reactions. The concomitant reactions to the two fragrance allergens suggest multiple sensitizations, which most likely reflect the exposure to the different fragrance materials in various types of consumer products. This is in accordance with what is generally seen for patch test reactions to fragrance...

  3. [Regulation of terpene metabolism]. Annual progress report, March 15, 1991--March 14, 1992

    Energy Technology Data Exchange (ETDEWEB)

    Croteau, R.

    1992-12-31

    This report describes accomplishments over the past year on understanding of terpene synthesis in mint plants and sage. Specifically reported are the fractionation of 4-S-limonene synthetase, the enzyme responsible for the first committed step to monoterpene synthesis, along with isolation of the corresponding RNA and DNA cloning of its gene; the localization of the enzyme within the oil glands, regulation of transcription and translation of the synthetase, the pathway to camphor biosynthesis,a nd studies on the early stages and branch points of the isoprenoid pathway.

  4. Reaction rates of ozone and terpenes adsorbed to model indoor surfaces.

    Science.gov (United States)

    Springs, M; Wells, J R; Morrison, G C

    2011-08-01

    Reaction rates and reaction probabilities have been quantified on model indoor surfaces for the reaction of ozone with two monoterpenes (Δ(3) -carene and d-limonene). Molar surface loadings were obtained by performing breakthrough experiments in a plug-flow reactor (PFR) packed with beads of glass, polyvinylchloride or zirconium silicate. Reaction rates and probabilities were determined by equilibrating the PFR with both the terpene and the ozone and measuring the ozone consumption rate. To mimic typical indoor conditions, temperatures of 20, 25, and 30°C were used in both types of experiments along with a relative humidity ranging from 10% to 80%. The molar surface loading decreased with increased relative humidity, especially on glass, suggesting that water competed with the terpenes for adsorption sites. The ozone reactivity experiments indicate that higher surface loadings correspond with higher ozone uptake. The reaction probability for Δ(3) -carene with ozone ranged from 2.9 × 10(-6) to 3.0 × 10(-5) while reaction probabilities for d-limonene ranged from 2.8 × 10(-5) to 3.0 × 10(-4) . These surface reaction probabilities are roughly 10-100 times greater than the corresponding gas-phase values. Extrapolation of these results to typical indoor conditions suggests that surface conversion rates may be substantial relative to gas-phase rates, especially for lower volatility terpenoids. At present, it is unclear how important heterogeneous reactions will be in influencing indoor concentrations of terpenes, ozone and their reaction products. We observe that surface reaction probabilities were 10 to 100 times greater than their corresponding gas-phase values. Thus indoor surfaces do enhance effective reaction rates and adsorption of terpenes will increase ozone flux to otherwise low-reactivity surfaces. Extrapolation of these results to typical indoor conditions suggests that surface conversion rates may be substantial relative to gas-phase rates, especially

  5. Terpene content of wine from the aromatic grape variety ‘Irsai Oliver’ (Vitis vinifera L. depends on maceration time

    Directory of Open Access Journals (Sweden)

    Baron Mojmir

    2017-03-01

    Full Text Available This study deals with the determination of the content of both free and bound terpenes in berries and wine of the aromatic grapevine variety ‘Irsai Oliver’. Grapes were macerated in juice for different time intervals (viz. 0; 5; 12; 24 hours and thereafter processed to wine. The objective was to map the dependence of some selected terpenes on the period of maceration. Using gas chromatography, some nine organic compounds were detected. Attention was paid to contents of linalool (3,7-dimethylokta-1,6-dien-3-ol, 2,6-dimetyl-3,7-octadiene-2,6-diol, hotrienol ([(5E-3,7-dimethylocta-1,5,7-trien-3-yl] acetate, αterpineol (2-(4-Methyl-1-cyclohex-3-enylpropan-2-ol, β-citronellol (3,7-Dimethyloct-6-en-1-ol, nerol ((Z-3,7-dimethyl-2,6-octadien-1-ol, geraniol ((trans-3,7-dimethyl-2,6-oktadien-1-ol and epoxylinalool (2-(5-ethenyl-5-methyloxolan-2-ylpropan-2- ol: epoxylinalool 1 (trans-linalool oxide (furanoid cis-linalool oxide (furanoid and epoxylinalool 2 (trans-linalool oxide (pyranoid cis-linalool oxide (pyranoid. Some basic wine parameters (alcohol, pH, sugars and total acids were estimated as well. The terpene content in wine increased gradually with the period of maceration. The highest and the lowest amounts of terpenes were recorded after 24 hours of maceration and no maceration, respectively. The terpene glycosides content was higher than that of the aglycones. Linalool and 2,6-dimetyl-3,7-octadiene-2,6-diol were the most abundant terpenes.

  6. Substrate geometry controls the cyclization cascade in multiproduct terpene synthases from Zea mays.

    Science.gov (United States)

    Vattekkatte, Abith; Gatto, Nathalie; Köllner, Tobias G; Degenhardt, Jörg; Gershenzon, Jonathan; Boland, Wilhelm

    2015-06-07

    Multiproduct terpene synthases TPS4-B73 and TPS5-Delprim from maize (Zea mays) catalyze the conversion of farnesyl diphosphate (FDP) and geranyl diphosphate (GDP) into a complex mixture of sesquiterpenes and monoterpenes, respectively. Various isotopic and geometric isomers of natural substrates like (2Z)-[2-(2)H]- and [2,4,4,9,9,9-(2)H6]-(GDP) and (2Z,6E)-[2-(2)H]- and [2,4,4,13,13,13-(2)H6]-(FDP) were synthesized analogous to presumptive reaction intermediates. On incubation with labeled (2Z) substrates, TPS4 and TPS5 showed much lower kinetic isotope effects than the labeled (2E) substrates. Interestingly, the products arising from the deuterated (2Z)-precursors revealed a distinct preference for cyclic products and exhibited an enhanced turnover on comparison with natural (2E)-substrates. This increase in the efficiency due to (2Z) configuration emphasizes the rate limiting effect of the initial (2E) → (2Z) isomerization step in the reaction cascade of the multiproduct terpene synthases. Apart from turnover advantages, these results suggest that substrate geometry can be used as a tool to optimize the biosynthetic reaction cascade towards valuable cyclic terpenoids.

  7. Phospholipids and terpenes modulate Caco-2 transport of açaí anthocyanins.

    Science.gov (United States)

    Cardona, Jorge A; Mertens-Talcott, Susanne U; Talcott, Stephen T

    2015-05-15

    Anthocyanins (ANC) are common polyphenolics in plants, but are poorly absorbed into the bloodstream upon consumption. Phospholipids (PL) and terpenes (TP) may serve as enhancing agents in absorption. This study evaluated their role in transepithelial transport within a Caco-2 cell monolayer-model system and impact on ANC stability. Açaí fruit ANC were isolated and found to transport, at a low rate (1.22%), in the absence of soy lecithin phospholipids and Valencia orange terpenes, yet their addition significantly increased the transport of both cyanidin-3-glucoside and cyanidin-3-rutinoside. The best transport results (5.21%) were observed when combinations of PL (5000 mg/l) and TP (50mg/l) were used. The presence of PL and TP had no influence on ANC degradation over a 40 day storage period. Results demonstrated the potential of PL and TP to increase intestinal transport of ANC, and present advancement towards the formulation of functional foods that support improved ANC absorption. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Terpene-induced porphyria and the illness of Vincent van Gogh

    Energy Technology Data Exchange (ETDEWEB)

    Lambrecht, R.; Cable, E.; Cable, J.; Clements, E.; Donohue, S.; Greene, Y.; Srivastava, K.; Arnold, W.; Bonkovsky, H. (Univ. of Massachusetts Medical Center, Worcester (United States) Univ. of Kansas Medical Center, Kansas City (United States))

    1992-01-01

    Vincent van Gogh suffered from recurrent bouts of an illness that may have been acute porphyria and abused camphor and alcohol, the latter particularly in the form of absinthe, a liqueur distilled from wormwood that was popular in 19th C France. To learn whether camphor or terpenes found in absinthe are porphyrogenic, the authors studied them in cultures of chick embryo liver cells. All were found to be porphyrogenic, especially in the presence of deferoxamine. The terpenes also induced the activity and protein amount of 5-aminolevulinate synthase and heme oxygenase, and induced activities of benzphetamine demethylase. The degree of porphyrin and enzyme induction produced by 1mM camphor was similar to that produced by 50uM glutethimide, a potent porphyrogen. Potency of pinene and thujone were lower. Camphor and glutethimide both produced accumulations of 8- and 7-COOH porphyrins, whereas pinene and thujone produced 4- and 2-COOH porphyrin accumulation. The authors conclude that camphor, pinen and thujone are porphyrogenic, cable of exacerbating acute porphyria, and may have done so in van Gogh.

  9. Surface chemistry of a pine-oil cleaner and other terpene mixtures with ozone on vinyl flooring tiles.

    Science.gov (United States)

    Ham, Jason E; Wells, J Raymond

    2011-04-01

    Indoor environments are dynamic reactors where consumer products (such as cleaning agents, deodorants, and air fresheners) emit volatile organic compounds (VOCs) that can subsequently interact with indoor oxidants such as ozone (O(3)), hydroxyl radicals, and nitrate radicals. Typically, consumer products consist of mixtures of VOCs and semi-VOCs which can react in the gas-phase or on surfaces with these oxidants to generate a variety of oxygenated products. In this study, the reaction of a pine-oil cleaner (POC) with O(3) (100ppb) on a urethane-coated vinyl flooring tile was investigated at 5% and 50% relative humidity. These results were compared to previous α-terpineol+O(3) reactions on glass and vinyl surfaces. Additionally, other terpene and terpene alcohol mixtures were formulated to understand the emission profiles as seen in the POC data. Results showed that the α-terpineol+O(3) reaction products were the prominent species that were also observed in the POC/O(3) surface experiments. Furthermore, α-terpineol+O(3) reactions generate the largest fraction of oxygenated products even in equal mixtures of other terpene alcohols. This finding suggests that the judicial choice of terpene alcohols for inclusion in product formulations may be useful in reducing oxidation product emissions. Published by Elsevier Ltd.

  10. Engineering Escherichia coli for the production of terpene mixture enriched in caryophyllene and caryophyllene alcohol as potential aviation fuel compounds.

    Science.gov (United States)

    Wu, Weihua; Liu, Fang; Davis, Ryan W

    2018-06-01

    Recent studies have revealed that caryophyllene and its stereoisomers not only exhibit multiple biological activities but also have desired properties as renewable candidates for ground transportation and jet fuel applications. This study presents the first significant production of caryophyllene and caryolan-1-ol by an engineered E. coli with heterologous expression of mevalonate pathway genes with a caryophyllene synthase and a caryolan-1-ol synthase. By optimizing metabolic flux and fermentation parameters, the engineered strains yielded 449 mg/L of total terpene, including 406 mg/L sesquiterpene with 100 mg/L caryophyllene and 10 mg/L caryolan-1-ol. Furthermore, a marine microalgae hydrolysate was used as the sole carbon source for the production of caryophyllene and other terpene compounds. Under the optimal fermentation conditions, 360 mg/L of total terpene, 322 mg/L of sesquiterpene, and 75 mg/L caryophyllene were obtained from the pretreated algae hydrolysates. The highest yields achieved on the biomass basis were 48 mg total terpene/g algae and 10 mg caryophyllene/g algae and the caryophyllene yield is approximately ten times higher than that from plant tissues by solvent extraction. The study provides a sustainable alternative for production of caryophyllene and its alcohol from microalgae biomass as potential candidates for next generation aviation fuels.

  11. Palladium-catalysed telomerisation of isoprene with glycerol and polyethylene glycol: A facile route to new terpene derivatives

    NARCIS (Netherlands)

    Gordillo, A.; Durán Páchon, L.; de Jesus, E.; Rothenberg, G.

    2009-01-01

    We present here the first example of the telomerisation of isoprene with glycerol and polyethylene glycol (PEG-200), opening a facile route to new terpene structures, based on a combination of renewable and petroleum-based feedstocks. The reaction is catalysed by a palladium-carbene complex.

  12. Evolution of the Cannabinoid and Terpene Content during the Growth of Cannabis sativa Plants from Different Chemotypes

    NARCIS (Netherlands)

    Aizpurua-Olaizola, Oier; Soydaner, Umut; Öztürk, Ekin; Schibano, Daniele; Simsir, Yilmaz; Navarro, Patricia; Etxebarria, Nestor; Usobiaga, Aresatz

    2016-01-01

    The evolution of major cannabinoids and terpenes during the growth of Cannabis sativa plants was studied. In this work, seven different plants were selected: three each from chemotypes I and III and one from chemotype II. Fifty clones of each mother plant were grown indoors under controlled

  13. Co-Compartmentation of Terpene Biosynthesis and Storage via Synthetic Droplet

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Cheng [Texas; amp,M Agrilife Synthetic and Systems Biology Innovation Hub, Texas A& amp,M University, College Station, Texas 77843, United States; Department; amp,M University, College Station, Texas 77843, United States; Institute; amp,M University, College Station, Texas 77843, United States; Kim, YongKyoung [Texas; amp,M Agrilife Synthetic and Systems Biology Innovation Hub, Texas A& amp,M University, College Station, Texas 77843, United States; Department; amp,M University, College Station, Texas 77843, United States; Institute; amp,M University, College Station, Texas 77843, United States; Zeng, Yining [Biosciences; Li, Man [Texas; amp,M Agrilife Synthetic and Systems Biology Innovation Hub, Texas A& amp,M University, College Station, Texas 77843, United States; Department; amp,M University, College Station, Texas 77843, United States; Institute; amp,M University, College Station, Texas 77843, United States; Wang, Xin [Texas; amp,M Agrilife Synthetic and Systems Biology Innovation Hub, Texas A& amp,M University, College Station, Texas 77843, United States; Department; amp,M University, College Station, Texas 77843, United States; Institute; amp,M University, College Station, Texas 77843, United States; Hu, Cheng [Texas; amp,M Agrilife Synthetic and Systems Biology Innovation Hub, Texas A& amp,M University, College Station, Texas 77843, United States; Department; amp,M University, College Station, Texas 77843, United States; Institute; amp,M University, College Station, Texas 77843, United States; Gorman, Connor [Texas; amp,M Agrilife Synthetic and Systems Biology Innovation Hub, Texas A& amp,M University, College Station, Texas 77843, United States; Department; amp,M University, College Station, Texas 77843, United States; Institute; amp,M University, College Station, Texas 77843, United States; Dai, Susie Y. [State; Ding, Shi-You [Department; Yuan, Joshua S. [Texas; amp,M Agrilife Synthetic and Systems Biology Innovation Hub, Texas A& amp,M University, College Station, Texas 77843, United States; Department; amp,M University, College Station, Texas 77843, United States; Institute; amp,M University, College Station, Texas 77843, United States

    2018-02-16

    Traditional bioproduct engineering focuses on pathway optimization, yet is often complicated by product inhibition, downstream consumption, and the toxicity of certain products. Here, we present the co-compartmentation of biosynthesis and storage via a synthetic droplet as an effective new strategy to improve the bioproduct yield, with squalene as a model compound. A hydrophobic protein was designed and introduced into the tobacco chloroplast to generate a synthetic droplet for terpene storage. Simultaneously, squalene biosynthesis enzymes were introduced to chloroplasts together with the droplet-forming protein to co-compartmentalize the biosynthesis and storage of squalene. The strategy has enabled a record yield of squalene at 2.6 mg/g fresh weight without compromising plant growth. Confocal fluorescent microscopy imaging, stimulated Raman scattering microscopy, and droplet composition analysis confirmed the formation of synthetic storage droplet in chloroplast. The co-compartmentation of synthetic storage droplet with a targeted metabolic pathway engineering represents a new strategy for enhancing bioproduct yield.

  14. P450 fingerprinting method for rapid discovery of terpene hydroxylating P450 catalysts with diversified regioselectivity.

    Science.gov (United States)

    Zhang, Kaidong; El Damaty, Shady; Fasan, Rudi

    2011-03-16

    Engineered P450 enzymes constitute attractive catalysts for the selective oxidation of unactivated C-H bonds in complex molecules. A current bottleneck in the use of P450 catalysis for chemical synthesis is the time and effort required to identify the P450 variant(s) with the desired level of activity and selectivity. In this report, we describe a method to map the active site configuration of engineered P450 variants in high throughput using a set of semisynthetic chromogenic probes. Through analysis of the resulting 'fingerprints', reliable predictions can be made regarding the reactivity of these enzymes toward complex substrates structurally related to the fingerprint probes. In addition, fingerprint analysis offers a convenient and time-effective means to assess the regioselectivity properties of the fingerprinted P450s. The described approach can represent a valuable tool to expedite the discovery of P450 oxidation catalysts for the functionalization of relevant natural products such as members of the terpene family.

  15. Stingless bees use terpenes as olfactory cues to find resin sources.

    Science.gov (United States)

    Leonhardt, S D; Zeilhofer, S; Blüthgen, N; Schmitt, Thomas

    2010-09-01

    Insects largely rely on olfactory cues when seeking and judging information on nests, partners, or resources. Bees are known to use volatile compounds-besides visual cues-to find flowers suitable for pollen and nectar collection. Tropical stingless bees additionally collect large amounts of plant resins for nest construction, nest maintenance, nest defense, and to derive chemical constituents for their cuticular profiles. We here demonstrate that stingless bees of Borneo also use olfactory cues to find tree resins. They rely on volatile mono- and sesquiterpenes to locate or recognize known resin sources. Moreover, by modifying resin extracts, we found that stingless bees do not use the entire resin bouquet but relative proportions of several terpenes. In doing so, the bees are able to learn specific tree resin profiles and distinguish between tree species and partly even tree individuals.

  16. Assessing terpene content variability of whitebark pine in order to estimate representative sample size

    Directory of Open Access Journals (Sweden)

    Stefanović Milena

    2013-01-01

    Full Text Available In studies of population variability, particular attention has to be paid to the selection of a representative sample. The aim of this study was to assess the size of the new representative sample on the basis of the variability of chemical content of the initial sample on the example of a whitebark pine population. Statistical analysis included the content of 19 characteristics (terpene hydrocarbons and their derivates of the initial sample of 10 elements (trees. It was determined that the new sample should contain 20 trees so that the mean value calculated from it represents a basic set with a probability higher than 95 %. Determination of the lower limit of the representative sample size that guarantees a satisfactory reliability of generalization proved to be very important in order to achieve cost efficiency of the research. [Projekat Ministarstva nauke Republike Srbije, br. OI-173011, br. TR-37002 i br. III-43007

  17. Environmental life cycle optimization of essential terpene oils produced by the macroalga Ochtodes secundiramea.

    Science.gov (United States)

    Pérez-López, Paula; Jeffryes, Clayton; Agathos, Spiros N; Feijoo, Gumersindo; Rorrer, Gregory; Moreira, María Teresa

    2016-01-15

    The macroalga Ochtodes secundiramea is a well-known producer of essential terpene oils with promising biological activities and similar applications to those of microalgal biocompounds in the pharmaceutical, food or cosmetics sectors. This study assesses the environmental impacts associated with the production of five essential terpene oils (myrcene, 10Z-bromomyrcene, 10E-bromo-3-chloromyrcene, apakaochtodene B and acyclic C10H14Br2) by O. secundiramea cultivated in a closed airlift photobioreactor with artificial illumination. The results of the life cycle assessment (LCA) allowed analyzing the effect of implementing a semi-continuous operation on several stages of the life cycle of the products, which may lead to impact reductions from 1% up to 25%. Regarding the most problematic aspects of the process, the cultivation in the photobioreactor (S4) was identified as the main stage responsible for the environmental burdens, with contributions ranging between 60% and 80% of the total impacts for a semi-continuous production maintained during one year of operation. The electricity supply is the key activity affecting eight of the ten assessed categories and involves between 50% and 60% of the impact of the process. S4 is the main cause of the high energy requirements, with 86% of the total electricity consumption. Additionally, several scenarios aiming at improving the environmental profile of the system were evaluated. The application of LCA finally led to the proposal of two optimized scenarios with improvements between 8% and 40% with respect to the baseline case study. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Application of terpene-induced cell for enhancing biodegradation of TCE contaminated soil

    Directory of Open Access Journals (Sweden)

    Ekawan Luepromchai

    2004-02-01

    Full Text Available Trichloroethylene (TCE, a chlorinated solvent, is a major water pollutant originating from spillage and inappropriate disposal of dry cleaning agents, degreasing solvents, and paint strippers. Due to its widespread contamination and potential health threat, remediation technology to clean-up TCE is necessary. Aerobic biodegradation of TCE is reported to occur via cometabolism, by which TCE degrading bacteria utilize other compounds such as toluene, phenol, and methane as growth substrate and enzyme inducer. Although toluene is reported to be the most effective inducer, it is regulated as a hazardous material and should not be applied to the environment. The objectives of this study were to identify an alternative enzyme inducer as well as to apply the induced bacteria for degradation of TCE in contaminated soil. We investigated the effect of terpenes, the main components in volatile essential oils of plants, on induction of TCE degradation in Rhodococcus gordoniae P3, a local Gram (+ bacterium. Selected terpenes including cumene, limonene, carvone and pinene at various concentrations were used in the study. Results from liquid culture showed that 25 mg l-1 cumeneinduced R. gordoniae P3 cells resulted in 75% degradation of 10 ppm TCE within 24 hrs. Soil microcosms were later employed to investigate the ability of cumene to enhance TCE biodegradation in the environment. There were two bioremediation treatments studied, including bioaugmentation, the inoculation of cumeneinduced R. gordoniae P3, and biostimulation, the addition of cumene to induce soil indigenous microorganisms to degrade TCE. Bioaugmentation and biostimulation were shown to accelerate TCE reduction significantly more than control treatment at the beginning of study. The results suggest that cumene-induced R. gordoniae P3 and cumene can achieve rapid TCE biodegradation.

  19. Impact of biogenic terpene emissions from Brassica napus on tropospheric ozone over Saxony (Germany): numerical investigation.

    Science.gov (United States)

    Renner, Eberhard; Münzenberg, Annette

    2003-01-01

    The role of biogenic emissions in tropospheric ozone production is currently under discussion and major aspects are not well understood yet. This study aims towards the estimation of the influence of biogenic emissions on tropospheric ozone concentrations over Saxony in general and of biogenic emissions from brassica napus in special. MODELLING TOOLS: The studies are performed by utilizing a coupled numerical modelling system consisting of the meteorological model METRAS and the chemistry transport model MUSCAT. For the chemical part, the Euro-RADM algorithm is used. EMISSIONS: Anthropogenic and biogenic emissions are taken into account. The anthropogenic emissions are introduced by an emission inventory. Biogenic emissions, VOC and NO, are calculated within the chemical transport model MUSCAT at each time step and in each grid cell depending on land use type and on the temperature. The emissions of hydrocarbons from forest areas as well as biogenic NO especially from agricultural grounds are considered. Also terpene emissions from brassica napus fields are estimated. SIMULATION SETUP AND METEOROLOGICAL CONDITIONS: The simulations were performed over an area with an extension of 160 x 140 km2 which covers the main parts of Saxony and neighboring areas of Brandenburg, Sachsen-Anhalt and Thuringia. Summer smog with high ozone concentrations can be expected during high pressure conditions on hot summer days. Typical meteorological conditions for such cases were introduced in an conceptual way. It is estimated that biogenic emissions change tropospheric ozone concentrations in a noticeable way (up to 15% to 20%) and, therefore, should not be neglected in studies about tropospheric ozone. Emissions from brassica napus do have a moderate potential to enhance tropospheric ozone concentrations, but emissions are still under consideration and, therefore, results vary to a high degree. Summing up, the effect of brassica napus terpene emissions on ozone concentrations is

  20. Engineering a Synthetic Microbial Consortium for Comprehensive Conversion of Algae Biomass into Terpenes for Advanced Biofuels and Bioproducts

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Weihua [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Wu, Benjamin Chiau-Pin [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Davis, Ryan Wesley [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2015-10-01

    Recent strategies for algae-based biofuels have primarily focused on biodiesel production by exploiting high algal lipid yields under nutrient stress conditions. However, under conditions supporting robust algal biomass accumulation, carbohydrate and proteins typically comprise up to ~80% of the ash-free dry weight of algae biomass. Therefore, comprehensive utilization of algal biomass for production of multipurpose intermediate- to high-value bio-based products will promote scale-up of algae production and processing to commodity volumes. Terpenes are hydrocarbon and hydrocarbon-like (C:O>10:1) compounds with high energy density, and are therefore potentially promising candidates for the next generation of value added bio-based chemicals and “drop-in” replacements for petroleum-based fuels. In this study, we demonstrated the feasibility of bioconversion of proteins into sesquiterpene compounds as well as comprehensive bioconversion of algal carbohydrates and proteins into biofuels. To achieve this, the mevalonate pathway was reconstructed into an E. coli chassis with six different terpene synthases (TSs). Strains containing the various TSs produced a spectrum of sesquiterpene compounds in minimal medium containing amino acids as the sole carbon source. The sesquiterpene production was optimized through three different regulation strategies using chamigrene synthase as an example. The highest total terpene titer reached 166 mg/L, and was achieved by applying a strategy to minimize mevalonate accumulation in vivo. The highest yields of total terpene were produced under reduced IPTG induction levels (0.25 mM), reduced induction temperature (25°C), and elevated substrate concentration (20 g/L amino acid mixture). A synthetic bioconversion consortium consisting of two engineering E. coli strains (DH1-TS and YH40-TS) with reconstructed terpene biosynthetic pathways was designed for comprehensive single-pot conversion of algal carbohydrates and proteins to

  1. Applying mechanistic models in bioprocess development

    DEFF Research Database (Denmark)

    Lencastre Fernandes, Rita; Bodla, Vijaya Krishna; Carlquist, Magnus

    2013-01-01

    The available knowledge on the mechanisms of a bioprocess system is central to process analytical technology. In this respect, mechanistic modeling has gained renewed attention, since a mechanistic model can provide an excellent summary of available process knowledge. Such a model therefore......, experimental data from Saccharomyces cerevisiae fermentations are used. The data are described with the well-known model of Sonnleitner and Käppeli (Biotechnol Bioeng 28:927-937, 1986) and the model is analyzed further. The methods used are generic, and can be transferred easily to other, more complex case...

  2. Comparison of soxhlet, ultrasound-assisted and pressurized liquid extraction of terpenes, fatty acids and Vitamin E from Piper gaudichaudianum Kunth.

    Science.gov (United States)

    Péres, Valéria Flores; Saffi, Jenifer; Melecchi, Maria Inês S; Abad, Fernanda C; de Assis Jacques, Rosângela; Martinez, Migdalia M; Oliveira, Eniz Conceição; Caramão, Elina B

    2006-02-10

    This paper describes a comparative study of extraction methods of terpenes (terpenic alcohols and phytosterols), fatty acids and Vitamin E from leaves of Piper gaudichaudianum Kunth. The analysis of extracts was done by gas chromatography with mass spectrometric detection. The identification and quantification was made by co-injections of the extract with certified standards. The use of pressurized liquid extraction (PLE; Dionex trade name: ASE, for accelerated solvent extraction) decrease significantly the total time of extraction, the amount of solvent and the manipulation of sample and solvents in comparison with soxhlet (SE) and ultrasound-assisted (USE). In addition, PLE was more effective for the extractions of terpenes (terpenic alcohols and phytosterols), fatty acids and Vitamin E.

  3. Antioxidant, antibacterial and cytotoxic potential of silver nanoparticles synthesized using terpenes rich extract of Lantana camara L. leaves

    Directory of Open Access Journals (Sweden)

    Patil Shriniwas P.

    2017-07-01

    Full Text Available Several attempts have been made for green synthesis of silver nanoparticles (AgNPs using different plant extracts. Present study revealed that, antioxidant, antibacterial and cytotoxic AgNPs were synthesized using terpenes-rich extract (TRE of environmentally notorious Lantana camara L. leaves. AgNPs were characterized by advanced techniques like UV–Visible and Infra red spectroscopy; XRD, SEM techniques as terpenes coated sphere shaped NPs with average diameter 425 nm. Further, on evaluation, AgNPs were found to exhibit dose – dependent antioxidant potential, good to moderate antibacterial activity against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa; and toxicity on Brine shrimp (A. salinanauplii with LD50 value 514.50 µg/ml.

  4. Decreased rates of terpene emissions in Ornithopus compressus L. and Trifolium striatum L. by ozone exposure and nitrogen fertilization.

    Science.gov (United States)

    Llusia, Joan; Bermejo-Bermejo, Victoria; Calvete-Sogo, Héctor; Peñuelas, Josep

    2014-11-01

    Increasing tropospheric ozone (O3) and nitrogen soil availability (N) are two of the main drivers of global change. They both may affect gas exchange, including plant emission of volatiles such as terpenes. We conducted an experiment using open-top chambers to analyze these possible effects on two leguminous species of Mediterranean pastures that are known to have different O3 sensitivity, Ornithopus compressus and Trifolium striatum. O3 exposure and N fertilization did not affect the photosynthetic rates of O. compressus and T. striatum, although O3 tended to induce an increase in the stomatal conductance of both species, especially T. striatum, the most sensitive species. O3 and N soil availability reduced the emission of terpenes in O. compressus and T. striatum. If these responses are confirmed as a general pattern, O3 could affect the competitiveness of these species. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Thermodynamic, kinetic and mechanistic investigations of ...

    Indian Academy of Sciences (India)

    J. Chem. Sci. Vol. 128, No. 3, March 2016, pp. 477–485. c Indian Academy of Sciences. DOI 10.1007/s12039-016-1044-x. Thermodynamic, kinetic and mechanistic ... The kinetics of oxidation of piperazine by the copper complex, diperiodatocuprate(III) in alkaline ... of this drug by DPC, there is a need for understanding.

  6. Mechanistic aspects of ionic reactions in flames

    DEFF Research Database (Denmark)

    Egsgaard, H.; Carlsen, L.

    1993-01-01

    Some fundamentals of the ion chemistry of flames are summarized. Mechanistic aspects of ionic reactions in flames have been studied using a VG PlasmaQuad, the ICP-system being substituted by a simple quartz burner. Simple hydrocarbon flames as well as sulfur-containing flames have been investigated...

  7. Relative expression of genes of terpene metabolism in different tissues of Artemisia annua L.

    Science.gov (United States)

    Olofsson, Linda; Engström, Alexander; Lundgren, Anneli; Brodelius, Peter E

    2011-03-09

    Recently, Artemisia annua L. (annual or sweet wormwood) has received increasing attention due to the fact that the plant produces the sesquiterpenoid endoperoxide artemisinin, which today is widely used for treatment of malaria. The plant produces relatively small amounts of artemisinin and a worldwide shortage of the drug has led to intense research in order to increase the yield of artemisinin. In order to improve our understanding of terpene metabolism in the plant and to evaluate the competition for precursors, which may influence the yield of artemisinin, we have used qPCR to estimate the expression of 14 genes of terpene metabolism in different tissues. The four genes of the artemisinin biosynthetic pathway (amorpha-4,11-diene synthase, amorphadiene-12-hydroxylase, artemisinic aldehyde ∆11(13) reductase and aldehyde dehydrogenase 1) showed remarkably higher expression (between ~40- to ~500-fold) in flower buds and young leaves compared to other tissues (old leaves, stems, roots, hairy root cultures). Further, dihydroartemisinic aldehyde reductase showed a very high expression only in hairy root cultures. Germacrene A and caryophyllene synthase were mostly expressed in young leaves and flower buds while epi-cedrol synthase was highly expressed in old leaves. 3-Hydroxy-3-methyl-glutaryl coenzyme A reductase exhibited lower expression in old leaves compared to other tissues. Farnesyldiphosphate synthase, squalene synthase, and 1-deoxy-D-xylulose-5-phosphate reductoisomerase showed only modest variation in expression in the different tissues, while expression of 1-deoxy-D-xylulose-5-phosphate synthase was 7-8-fold higher in flower buds and young leaves compared to old leaves. Four genes of artemisinin biosynthesis were highly expressed in flower buds and young leaves (tissues showing a high density of glandular trichomes). The expression of dihydroartemisinic aldehyde reductase has been suggested to have a negative effect on artemisinin production through

  8. Chemodiversity of a Scots pine stand and implications for terpene air concentrations

    Science.gov (United States)

    Bäck, J.; Aalto, J.; Henriksson, M.; Hakola, H.; He, Q.; Boy, M.

    2012-02-01

    Atmospheric chemistry in background areas is strongly influenced by natural vegetation. Coniferous forests are known to produce large quantities of volatile vapors, especially terpenes. These compounds are reactive in the atmosphere, and contribute to the formation and growth of atmospheric new particles. Our aim was to analyze the variability of mono- and sesquiterpene emissions between Scots pine trees, in order to clarify the potential errors caused by using emission data obtained from only a few trees in atmospheric chemistry models. We also aimed at testing if stand history and seed origin has an influence on the chemotypic diversity. The inherited, chemotypic variability in mono- and sesquiterpene emission was studied in a seemingly homogeneous 48 yr-old stand in Southern Finland, where two areas differing in their stand regeneration history could be distinguished. Sampling was conducted in August 2009. Terpene concentrations in the air had been measured at the same site for seven years prior to branch sampling for chemotypes. Two main compounds, α-pinene and Δ3-carene formed together 40-97% of the monoterpene proportions in both the branch emissions and in the air concentrations. The data showed a bimodal distribution in emission composition, in particular in Δ3-carene emission within the studied population. 10% of the trees emitted mainly α-pinene and no Δ3-carene at all, whereas 20% of the trees where characterized as high Δ3-carene emitters (Δ3-carene forming >80% of total emitted monoterpene spectrum). An intermediate group of trees emitted equal amounts of both α-pinene and Δ3-carene. The emission pattern of trees at the area established using seeding as the artificial regeneration method differed from the naturally regenerated or planted trees, being mainly high Δ3-carene emitters. Some differences were also seen in e.g. camphene and limonene emissions between chemotypes, but sesquiterpene emissions did not differ significantly between trees

  9. Relative expression of genes of terpene metabolism in different tissues of Artemisia annua L

    Science.gov (United States)

    2011-01-01

    Background Recently, Artemisia annua L. (annual or sweet wormwood) has received increasing attention due to the fact that the plant produces the sesquiterpenoid endoperoxide artemisinin, which today is widely used for treatment of malaria. The plant produces relatively small amounts of artemisinin and a worldwide shortage of the drug has led to intense research in order to increase the yield of artemisinin. In order to improve our understanding of terpene metabolism in the plant and to evaluate the competition for precursors, which may influence the yield of artemisinin, we have used qPCR to estimate the expression of 14 genes of terpene metabolism in different tissues. Results The four genes of the artemisinin biosynthetic pathway (amorpha-4,11-diene synthase, amorphadiene-12-hydroxylase, artemisinic aldehyde ∆11(13) reductase and aldehyde dehydrogenase 1) showed remarkably higher expression (between ~40- to ~500-fold) in flower buds and young leaves compared to other tissues (old leaves, stems, roots, hairy root cultures). Further, dihydroartemisinic aldehyde reductase showed a very high expression only in hairy root cultures. Germacrene A and caryophyllene synthase were mostly expressed in young leaves and flower buds while epi-cedrol synthase was highly expressed in old leaves. 3-Hydroxy-3-methyl-glutaryl coenzyme A reductase exhibited lower expression in old leaves compared to other tissues. Farnesyldiphosphate synthase, squalene synthase, and 1-deoxy-D-xylulose-5-phosphate reductoisomerase showed only modest variation in expression in the different tissues, while expression of 1-deoxy-D-xylulose-5-phosphate synthase was 7-8-fold higher in flower buds and young leaves compared to old leaves. Conclusions Four genes of artemisinin biosynthesis were highly expressed in flower buds and young leaves (tissues showing a high density of glandular trichomes). The expression of dihydroartemisinic aldehyde reductase has been suggested to have a negative effect on

  10. Relative expression of genes of terpene metabolism in different tissues of Artemisia annua L

    Directory of Open Access Journals (Sweden)

    Lundgren Anneli

    2011-03-01

    Full Text Available Abstract Background Recently, Artemisia annua L. (annual or sweet wormwood has received increasing attention due to the fact that the plant produces the sesquiterpenoid endoperoxide artemisinin, which today is widely used for treatment of malaria. The plant produces relatively small amounts of artemisinin and a worldwide shortage of the drug has led to intense research in order to increase the yield of artemisinin. In order to improve our understanding of terpene metabolism in the plant and to evaluate the competition for precursors, which may influence the yield of artemisinin, we have used qPCR to estimate the expression of 14 genes of terpene metabolism in different tissues. Results The four genes of the artemisinin biosynthetic pathway (amorpha-4,11-diene synthase, amorphadiene-12-hydroxylase, artemisinic aldehyde ∆11(13 reductase and aldehyde dehydrogenase 1 showed remarkably higher expression (between ~40- to ~500-fold in flower buds and young leaves compared to other tissues (old leaves, stems, roots, hairy root cultures. Further, dihydroartemisinic aldehyde reductase showed a very high expression only in hairy root cultures. Germacrene A and caryophyllene synthase were mostly expressed in young leaves and flower buds while epi-cedrol synthase was highly expressed in old leaves. 3-Hydroxy-3-methyl-glutaryl coenzyme A reductase exhibited lower expression in old leaves compared to other tissues. Farnesyldiphosphate synthase, squalene synthase, and 1-deoxy-D-xylulose-5-phosphate reductoisomerase showed only modest variation in expression in the different tissues, while expression of 1-deoxy-D-xylulose-5-phosphate synthase was 7-8-fold higher in flower buds and young leaves compared to old leaves. Conclusions Four genes of artemisinin biosynthesis were highly expressed in flower buds and young leaves (tissues showing a high density of glandular trichomes. The expression of dihydroartemisinic aldehyde reductase has been suggested to have a

  11. Potential Contribution of Fish Feed and Phytoplankton to the Content of Volatile Terpenes in Cultured Pangasius (Pangasianodon hypophthalmus) and Tilapia (Oreochromis niloticus).

    Science.gov (United States)

    Podduturi, Raju; Petersen, Mikael A; Mahmud, Sultan; Rahman, Md Mizanur; Jørgensen, Niels O G

    2017-05-10

    Geosmin and 2-methylisoborneol are the most recognized off-flavors in freshwater fish, but terpenes may also contribute off-flavor in fish. We identified six monoterpenes, 11 sesquiterpenes, and three terpene-related compounds in pangasius and tilapia from aquaculture farms in Bangladesh. The concentrations of most of the volatiles were below published odor thresholds, except for α-pinene, limonene, β-caryophyllene, α-humulene, and β-ionone in tilapia, and limonene and β-ionone in pangasius. To identify sources of the terpenes, terpene profiles of fish feed and phytoplankton in the ponds were analyzed. In feed and mustard cake (feed ingredient), five monoterpenes and two sesquiterpenes were identified, and five of these compounds were also detected in the fish. In phytoplankton, 11 monoterpenes were found and three also occurred in the fish. The higher number of terpenes common to both fish and feed, than to fish and phytoplankton, suggests that feed was a more abundant source of odor-active terpenes in the fish than phytoplankton.

  12. Application of canonical discriminant analysis in differentiation of natural populations of Pinus nigra in Serbia based on terpene composition

    OpenAIRE

    Šarac, Z.; Bojović, S.; Nikolić, B.; Zlatković, B.; Marin, P.

    2014-01-01

    The canonical discriminant analysis (CDA) was performed in order to check the hypothesis of chemical separation infraspecific taxa of Pinus nigra J.F. Arnold (ssp. nigra, var. gocensis, ssp. pallasiana, and var. banatica) in Serbia based on variability of the needle terpenes. The CDA, which maximizes variations between a priori groups, showed division of seven native P. nigra populations into three groups, which belong to three taxonomically recognized taxa (ssp. nigra, ssp. pallasiana, and v...

  13. QCM-Arrays for Sensing Terpenes in Fresh and Dried Herbs via Bio-Mimetic MIP Layers

    Directory of Open Access Journals (Sweden)

    Naseer Iqbal

    2010-06-01

    Full Text Available A piezoelectric 10 MHz multichannel quartz crystal microbalance (MQCM, coated with six molecularly imprinted polystyrene artificial recognition membranes have been developed for selective quantification of terpenes emanated from fresh and dried Lamiaceae family species, i.e., rosemary (Rosmarinus Officinalis L., basil (Ocimum Basilicum and sage (Salvia Officinalis. Optimal e-nose parameters, such as layer heights (1–6 KHz, sensitivity

  14. Traceability of grass feeding in beef: terpenes, 2,3-octanedione and skatole accumulation in adipose tissue of young bulls

    OpenAIRE

    Cornu, Agnes; Kondjoyan, Nathalie; Agabriel, Jacques; Micol, Didier

    2011-01-01

    The development of analytical methods to verify the production system of meat products requires the identification of biomarkers that can trace the product's origin, and secondly the factors that govern the deposition of these markers in animal tissue need to be defined. In this study, 2,3-octanedione, skatole and terpenes were selected as biomarkers, and their deposition was investigated in bull calves reared under three different strategies. All of the animals were reared indoors until appr...

  15. Two terpene synthases are responsible for the major sesquiterpenes emitted from the flowers of kiwifruit (Actinidia deliciosa)

    Science.gov (United States)

    Nieuwenhuizen, Niels J.; Wang, Mindy Y.; Matich, Adam J.; Green, Sol A.; Chen, Xiuyin; Yauk, Yar-Khing; Beuning, Lesley L.; Nagegowda, Dinesh A.; Dudareva, Natalia; Atkinson, Ross G.

    2009-01-01

    Kiwifruit vines rely on bees for pollen transfer between spatially separated male and female individuals and require synchronized flowering to ensure pollination. Volatile terpene compounds, which are important cues for insect pollinator attraction, were studied by dynamic headspace sampling in the major green-fleshed kiwifruit (Actinidia deliciosa) cultivar ‘Hayward’ and its male pollinator ‘Chieftain’. Terpene volatile levels showed a profile dominated by the sesquiterpenes α-farnesene and germacrene D. These two compounds were emitted by all floral tissues and could be observed throughout the day, with lower levels at night. The monoterpene (E)-β-ocimene was also detected in flowers but was emitted predominantly during the day and only from petal tissue. Using a functional genomics approach, two terpene synthase (TPS) genes were isolated from a ‘Hayward’ petal EST library. Bacterial expression and transient in planta data combined with analysis by enantioselective gas chromatography revealed that one TPS produced primarily (E,E)-α-farnesene and small amounts of (E)-β-ocimene, whereas the second TPS produced primarily (+)-germacrene D. Subcellular localization using GFP fusions showed that both enzymes were localized in the cytoplasm, the site for sesquiterpene production. Real-time PCR analysis revealed that both TPS genes were expressed in the same tissues and at the same times as the corresponding floral volatiles. The results indicate that two genes can account for the major floral sesquiterpene volatiles observed in both male and female A. deliciosa flowers. PMID:19516075

  16. Secondary organic aerosol from ozone-initiated reactions with terpene-rich household products

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, Beverly; Coleman, Beverly K.; Lunden, Melissa M.; Destaillats, Hugo; Nazaroff, William W.

    2008-01-01

    We analyzed secondary organic aerosol (SOA) data from a series of small-chamber experiments in which terpene-rich vapors from household products were combined with ozone under conditions analogous to product use indoors. Reagents were introduced into a continuously ventilated 198 L chamber at steady rates. Consistently, at the time of ozone introduction, nucleation occurred exhibiting behavior similar to atmospheric events. The initial nucleation burst and growth was followed by a period in which approximately stable particle levels were established reflecting a balance between new particle formation, condensational growth, and removal by ventilation. Airborne particles were measured with a scanning mobility particle sizer (SMPS, 10 to 400 nm) in every experiment and with an optical particle counter (OPC, 0.1 to 2.0 ?m) in a subset. Parameters for a three-mode lognormal fit to the size distribution at steady state were determined for each experiment. Increasing the supply ozone level increased the steady-state mass concentration and yield of SOA from each product tested. Decreasing the air-exchange rate increased the yield. The steady-state fine-particle mass concentration (PM1.1) ranged from 10 to> 300 mu g m-3 and yields ranged from 5percent to 37percent. Steady-state nucleation rates and SOA mass formation rates were on the order of 10 cm-3 s-1 and 10 mu g m-3 min-1, respectively.

  17. Ganoderma applanatum terpenes protect mouse liver against benzo(α)pyren-induced oxidative stress and inflammation.

    Science.gov (United States)

    Ma, Jie-Qiong; Liu, Chan-Min; Qin, Zhi-Hong; Jiang, Ji-Hong; Sun, Yun-Zhi

    2011-05-01

    Ganoderma applanatum terpenes (GAT) have been reported to have many benefits and medicinal properties. In this study, we evaluated the protective effect of GAT against benzo(a)pyrene (BaP) induced oxidative stress and inflammation in mouse liver, and explored the potential mechanism of its action. Our data showed that GAT significantly decreased levels of ALT and AST in serum and the liver histological injury in BaP-treated mice. GAT markedly decreased the levels of ROS, MDA and lowered the GSH/GSSG ratio in the liver of BaP-treated mice. Furthermore, GAT markedly inhibited the BaP-induced increase of Cu/Zn-SOD, CAT, GPx and GST activities in the mouse liver. Western blot analysis showed that GAT significantly inhibited inflammation by pressing the expression of IL-1β and COX-2 and inhibiting NF-κB translocation in the liver of BaP-treated mice. In conclusion, these results suggested that GAT could protect the mouse liver against BaP-induced injury by improving hepatic function, attenuating histopathologic changes, decreasing levels of ROS and MDA, renewing the activities of antioxidant enzymes and suppressing inflammatory response. Copyright © 2011 Elsevier B.V. All rights reserved.

  18. Oxidized limonene and oxidized linalool - concomitant contact allergy to common fragrance terpenes.

    Science.gov (United States)

    Bråred Christensson, Johanna; Karlberg, Ann-Therese; Andersen, Klaus E; Bruze, Magnus; Johansen, Jeanne D; Garcia-Bravo, Begoña; Giménez Arnau, Ana; Goh, Chee-Leok; Nixon, Rosemary; White, Ian R

    2016-05-01

    Limonene and linalool are common fragrance terpenes. Both oxidized R-limonene and oxidized linalool have recently been patch tested in an international setting, showing contact allergy in 5.2% and 6.9% of dermatitis patients, respectively. To investigate concomitant reactions between oxidized R-limonene and oxidized linalool in consecutive dermatitis patients. Oxidized R-limonene 3.0% (containing limonene hydroperoxides 0.33%) and oxidized linalool 6% (linalool hydroperoxides 1%) in petrolatum were tested in 2900 consecutive dermatitis patients in Australia, Denmark, Singapore, Spain, Sweden, and the United Kingdom. A total of 281 patients reacted to either oxidized R-limonene or oxidized linalool. Of these, 25% had concomitant reactions to both compounds, whereas 29% reacted only to oxidized R-limonene and 46% only to oxidized linalool. Of the 152 patients reacting to oxidized R-limonene, 46% reacted to oxidized linalool, whereas 35% of the 200 patients reacting to oxidized linalool also reacted to oxidized R-limonene. The majority of the patients (75%) reacted to only one of the oxidation mixtures, thus supporting the specificity of the reactions. The concomitant reactions to the two fragrance allergens suggest multiple sensitizations, which most likely reflect the exposure to the different fragrance materials in various types of consumer products. This is in accordance with what is generally seen for patch test reactions to fragrance materials. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. [Regulation of terpene metabolism]. Annual progress report, March 15, 1990--March 14, 1991

    Energy Technology Data Exchange (ETDEWEB)

    Croteau, R.

    1991-12-31

    During the last grant period, we have completed studies on the key pathways of monoterpene biosynthesis and catabolism in sage and peppermint, and have, by several lines of evidence, deciphered the rate-limiting step of each pathway. We have at least partially purified and characterized the relevant enzymes of each pathway. We have made a strong case, based on analytical, in vivo, and in vitro studies, that terpene accumulation depends upon the balance between biosynthesis and catabolism, and provided supporting evidence that these processes are developmentally-regulated and very closely associated with senescence of the oil glands. Oil gland ontogeny has been characterized at the ultrastructural level. We have exploited foliar-applied bioregulators to delay gland senescence, and have developed tissue explant and cell culture systems to study several elusive aspects of catabolism. We have isolated pure gland cell clusters and localized monoterpene biosynthesis and catabolism within these structures, and have used these preparations as starting materials for the purification to homogeneity of target ``regulatory`` enzymes. We have thus developed the necessary background knowledge, based on a firm understanding of enzymology, as well as the necessary experimental tools for studying the regulation of monoterpene metabolism at the molecular level. Furthermore, we are now in a position to extend our systematic approach to other terpenoid classes (C{sub 15}-C{sub 30}) produced by oil glands.

  20. The α-Terpineol to 1,8-Cineole Cyclization Reaction of Tobacco Terpene Synthases1

    Science.gov (United States)

    Piechulla, Birgit; Bartelt, Richard; Brosemann, Anne; Bouwmeester, Harro; Hippauf, Frank

    2016-01-01

    Flowers of Nicotiana species emit a characteristic blend including the cineole cassette monoterpenes. This set of terpenes is synthesized by multiproduct enzymes, with either 1,8-cineole or α-terpineol contributing most to the volatile spectrum, thus referring to cineole or terpineol synthase, respectively. To understand the molecular and structural requirements of the enzymes that favor the biochemical formation of α-terpineol and 1,8-cineole, site-directed mutagenesis, in silico modeling, and semiempiric calculations were performed. Our results indicate the formation of α-terpineol by a nucleophilic attack of water. During this attack, the α-terpinyl cation is stabilized by π-stacking with a tryptophan side chain (tryptophan-253). The hypothesized catalytic mechanism of α-terpineol-to-1,8-cineole conversion is initiated by a catalytic dyad (histidine-502 and glutamate-249), acting as a base, and a threonine (threonine-278) providing the subsequent rearrangement from terpineol to cineol by catalyzing the autoprotonation of (S)-(−)-α-terpineol, which is the favored enantiomer product of the recombinant enzymes. Furthermore, by site-directed mutagenesis, we were able to identify amino acids at positions 147, 148, and 266 that determine the different terpineol-cineole ratios in Nicotiana suaveolens cineole synthase and Nicotiana langsdorffii terpineol synthase. Since amino acid 266 is more than 10 Å away from the active site, an indirect effect of this amino acid exchange on the catalysis is discussed. PMID:27729471

  1. The α-Terpineol to 1,8-Cineole Cyclization Reaction of Tobacco Terpene Synthases.

    Science.gov (United States)

    Piechulla, Birgit; Bartelt, Richard; Brosemann, Anne; Effmert, Uta; Bouwmeester, Harro; Hippauf, Frank; Brandt, Wolfgang

    2016-12-01

    Flowers of Nicotiana species emit a characteristic blend including the cineole cassette monoterpenes. This set of terpenes is synthesized by multiproduct enzymes, with either 1,8-cineole or α-terpineol contributing most to the volatile spectrum, thus referring to cineole or terpineol synthase, respectively. To understand the molecular and structural requirements of the enzymes that favor the biochemical formation of α-terpineol and 1,8-cineole, site-directed mutagenesis, in silico modeling, and semiempiric calculations were performed. Our results indicate the formation of α-terpineol by a nucleophilic attack of water. During this attack, the α-terpinyl cation is stabilized by π-stacking with a tryptophan side chain (tryptophan-253). The hypothesized catalytic mechanism of α-terpineol-to-1,8-cineole conversion is initiated by a catalytic dyad (histidine-502 and glutamate-249), acting as a base, and a threonine (threonine-278) providing the subsequent rearrangement from terpineol to cineol by catalyzing the autoprotonation of (S)-(-)-α-terpineol, which is the favored enantiomer product of the recombinant enzymes. Furthermore, by site-directed mutagenesis, we were able to identify amino acids at positions 147, 148, and 266 that determine the different terpineol-cineole ratios in Nicotiana suaveolens cineole synthase and Nicotiana langsdorffii terpineol synthase. Since amino acid 266 is more than 10 Å away from the active site, an indirect effect of this amino acid exchange on the catalysis is discussed. © 2016 American Society of Plant Biologists. All Rights Reserved.

  2. Dry Deposition of Biogenic Terpenes via Cationic Oligomerization on Environmental Aqueous Surfaces.

    Science.gov (United States)

    Enami, Shinichi; Hoffmann, Michael R; Colussi, Agustín J

    2012-11-01

    Unraveling the complex interactions between the atmosphere and the biosphere is critical for predicting climate changes. Although it is well-recognized that the large amounts of biogenic volatile organic compounds (BVOCs) emitted by plants must play important roles in this regard, current atmospheric models fail to account for their fate due to missing chemical sinks. Here, we applied online electrospray mass spectrometry to monitor aqueous microjets exposed to gaseous monoterpenes (α-pinene, β-pinene, and d-limonene) and found that these BVOCs are readily protonated (to C10H17(+)) and undergo oligomerization (to C20H33(+) and C30H49(+)) upon colliding with the surface of pH < 4 microjets. By considering that the yields of all products show inflection points at pH ≈ 3.5 and display solvent kinetic hydrogen isotope effects larger than 2, we conclude that the oligomerization process is initiated by weakly hydrated hydronium ions, H3O(+), present at the gas-water interface. Present results provide a universal mechanism for the dry deposition of unsaturated BVOCs and may account for recent observations on the uptake of terpenes in forest canopies and over grassland.

  3. Terpene-mediated parasitoid host location behavior on transgenic and classically bred apple genotypes.

    Science.gov (United States)

    Vogler, Ute; Rott, Anja S; Gessler, Cesare; Dorn, Silvia

    2009-08-12

    Terpene-mediated interactions between transgenic or classically bred apple genotypes and associated insects were investigated. Apple genotypes were either resistant or susceptible to Venturia inaequalis that causes apple scab. They were subjected to infestation by Phyllonorycter leafminers and/or inoculation with V. inaequalis. Apple leaf extracts were analyzed by gas chromatography-mass spectrometry to quantify squalene, a triterpene known to mediate host location by Pholetesor parasitoids that are specialized on leafminers. Squalene contents in leafminer-infested leaves differed between the transgenic apple scab resistant line and a classically bred cultivar sharing the same resistance gene. This resistant cultivar showed an increase in squalene contents from healthy to leafminer-infested leaves. This was not the case in the transgenic resistant line. However, there was also no increase in the susceptible isogenic cultivar. Behavioral bioassays with parasitoid females also reflected these findings. Hence, alterations in leaf chemistry and corresponding responses of the parasitoid are apparent among classically bred cultivars, rather than in the genetically modified resistant line.

  4. Precision and accuracy of mechanistic-empirical pavement design

    CSIR Research Space (South Africa)

    Theyse, HL

    2006-09-01

    Full Text Available The availability of mechanistic-empirical pavement design methods is increasing internationally. Although mechanistic-empirical design does offer some insight into pavement behaviour and performance, at least more so than empirical design methods...

  5. Mechanistic fracture criteria for the failure of human cortical bone

    Energy Technology Data Exchange (ETDEWEB)

    Nalla, Ravi K.; Kinney, John H.; Ritchie, Robert O.

    2002-12-13

    A mechanistic understanding of fracture in human bone is critical to predicting fracture risk associated with age and disease. Despite extensive work, a mechanistic framework for describing how the underlying microstructure affects the failure mode in bone is lacking.

  6. Evolutionary and mechanistic theories of aging.

    Science.gov (United States)

    Hughes, Kimberly A; Reynolds, Rose M

    2005-01-01

    Senescence (aging) is defined as a decline in performance and fitness with advancing age. Senescence is a nearly universal feature of multicellular organisms, and understanding why it occurs is a long-standing problem in biology. Here we present a concise review of both evolutionary and mechanistic theories of aging. We describe the development of the general evolutionary theory, along with the mutation accumulation, antagonistic pleiotropy, and disposable soma versions of the evolutionary model. The review of the mechanistic theories focuses on the oxidative stress resistance, cellular signaling, and dietary control mechanisms of life span extension. We close with a discussion of how an approach that makes use of both evolutionary and molecular analyses can address a critical question: Which of the mechanisms that can cause variation in aging actually do cause variation in natural populations?

  7. Induction of Terpene Biosynthesis in Berries of Microvine Transformed with VvDXS1 Alleles

    Directory of Open Access Journals (Sweden)

    Lorenza Dalla Costa

    2018-01-01

    Full Text Available Terpenoids, especially monoterpenes, are major aroma-impact compounds in grape and wine. Previous studies highlighted a key regulatory role for grapevine 1-deoxy-D-xylulose 5-phosphate synthase 1 (VvDXS1, the first enzyme of the methylerythritol phosphate pathway for isoprenoid precursor biosynthesis. Here, the parallel analysis of VvDXS1 genotype and terpene concentration in a germplasm collection demonstrated that VvDXS1 sequence has a very high predictive value for the accumulation of monoterpenes and also has an influence on sesquiterpene levels. A metabolic engineering approach was applied by expressing distinct VvDXS1 alleles in the grapevine model system “microvine” and assessing the effects on downstream pathways at transcriptional and metabolic level in different organs and fruit developmental stages. The underlying goal was to investigate two potential perturbation mechanisms, the former based on a significant over-expression of the wild-type (neutral VvDXS1 allele and the latter on the ex-novo expression of an enzyme with increased catalytic efficiency from the mutated (muscat VvDXS1 allele. The integration of the two VvDXS1 alleles in distinct microvine lines was found to alter the expression of several terpenoid biosynthetic genes, as assayed through an ad hoc developed TaqMan array based on cDNA libraries of four aromatic cultivars. In particular, enhanced transcription of monoterpene, sesquiterpene and carotenoid pathway genes was observed. The accumulation of monoterpenes in ripe berries was higher in the transformed microvines compared to control plants. This effect is predominantly attributed to the improved activity of the VvDXS1 enzyme coded by the muscat allele, whereas the up-regulation of VvDXS1 plays a secondary role in the increase of monoterpenes.

  8. In vitro percutaneous absorption enhancement of propranolol hydrochloride through porcine epidermis by terpenes/ethanol.

    Science.gov (United States)

    Zhao, K; Singh, J

    1999-12-06

    The purpose of this study was to investigate the mechanism(s) of percutaneous absorption enhancement of propranolol hydrochloride (PHCL) across porcine epidermis by terpenes (e.g. menthone and limonene) in combination with ethanol. The in vitro percutaneous absorption experiments were performed using Franz diffusion cells. The solubility of PHCL in control and enhancer solutions was determined through high-performance liquid chromatography. Partitioning of PHCL to powdered SC from control or enhancer solutions was also determined in order to investigate the binding of PHCL to the SC from the SC/enhancer system. Fourier transform infrared spectroscopy (FT-IR) was employed to study the biophysical changes in stratum corneum (SC) lipids. The in vitro macroscopic barrier properties were investigated by measuring transepidermal water loss (TEWL) using Tewameter. Five percent menthone or limonene in combination with ethanol (EtOH) (menthone/EtOH or limonene/EtOH) significantly increased (P<0.05) the flux of PHCL through porcine epidermis in comparison to the control (EtOH). The partitioning of PHCL to the SC from the SC/enhancer system was also significantly greater than the SC/control system. The above enhancers showed a decrease in the peak heights and areas for both asymmetric and symmetric C-H stretching absorbances in comparison with the untreated SC, indicating the SC lipids extraction. Menthone/EtOH and limonene/EtOH enhanced (P<0.05) the in vitro TEWL through the epidermis in comparison to the control. Thus, an enhancement in the flux of PHCL by menthone/EtOH and limonene/EtOH is due to SC lipid extraction, macroscopic barrier perturbation, and improvement in the partitioning of the drug to the SC.

  9. In vitro inhibitory activity of terpenic derivatives against clinical and environmental strains of the Sporothrix schenkii complex.

    Science.gov (United States)

    Brilhante, Raimunda Sâmia Nogueira; Silva, Natalya Fechine; Marques, Francisca Jakelyne de Farias; Castelo-Branco, Débora de Souza Collares Maia; de Lima, Rita Amanda Chaves; Malaquias, Angela Donato Maia; Caetano, Erica Pacheco; Barbosa, Giovanna Riello; de Camargo, Zoilo Pires; Rodrigues, Anderson Messias; Monteiro, André Jalles; Bandeira, Tereza de Jesus Pinheiro Gomes; Cordeiro, Rossana de Aguiar; Sidrim, José Júlio Costa; Moreira, José Luciano Bezerra; Rocha, Marcos Fábio Gadelha

    2015-02-01

    Sporotrichosis is a subacute or chronic subcutaneous infection, caused by the fungus Sporothrix schenkii complex, occurring in human and animal tissues. Potassium iodide and itraconazole have been used as effective therapy for first-choice treatment, while amphotericin B may be indicated for disseminated infection. However, the adverse effects of potassium iodide and amphotericin B or the long duration of therapy with itraconazole often weigh against their use, leading to the search for alternatives for the treatment of severe infections. Terpinen-4-ol and farnesol are components of essential oils present in many plant species and have been described to have antifungal activity against microorganisms. In this study, 40 strains of Sporothrix spp. were tested for the susceptibility to terpinen-4-ol and farnesol. Changes in cytoplasmic membrane permeability were also investigated. Terpenes inhibited all Sporothrix strains with MIC values ranging from 87.9 to 1,429.8 μg/ml for terpinen-4-ol and from 0.003 to 0.222 μg/ml for farnesol. The MFC values ranged from 177.8 to 5,722.6 μg/ml and from 0.027 to 0.88 μg/ml, respectively, for terpinen-4-ol and farnesol. Farnesol was the most active compound for the Sporothrix strains. Significant loss of 260 and 280 nm-absorbing material did not occur after treatment with concentrations equivalent to the MIC and sub-MIC of the tested terpenes, when compared to corresponding untreated samples. The failure of terpenes to lyse Sporothrix cells suggests that their primary mechanism of action is not by causing irreversible cell membrane damage. Thus, new studies are needed to better understand the mechanisms involved in the antifungal activity. © The Author 2014. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  10. Terpene Profile, Leaf Anatomy, and Enzyme Activity of Resistant and Susceptible Cocoa Clonesto Vascular Streak Dieback Disease

    Directory of Open Access Journals (Sweden)

    Adi Prawoto

    2014-10-01

    Full Text Available Vascular-streak dieback (VSD, Oncobasidium theobromae is the most prevalent disease of Theobroma cacao L. in Indonesia. This study aims to analyze resistance mechanism to VSD based on terpene profile, leaf anatomy, chitinase, and peroxidase study. Resistant clones of Sulawesi 1 and Sca 6 and susceptible clones of ICS 60 and TSH 858 were used for terpene profile, leaf anatomy analysis, chitinase, peroxides, polyphenol, lignin, and cellulose analysis. Those clones and KEE 2, KKM 22 and ICS 13 were used for peroxides analysis. For trichome study, the resistant clones of Sulawesi 1, Sca 6, KEE 2, and KKM 22, and susceptible clones of ICS 60 and TSH 858 were used. GCMS analysis showed that chromatogram pattern of resistant and susceptible groups were quite similar, but resistant clones contained 22% more components than the susceptible ones. Resistant clones contained groups of pinene, decane, myrcene, and octadecanoic acid, while those substances on usceptible clones were absent. Trichome was thicker on younger leaf, and its density on the basal was higher than that on the middle and tip leaf parts. Trichome density of resistant clone was not always thicker than that of susceptible ones. On resistant clones, stomatal density was lower and width of stomate pits was narrower, while thickness of epidermis layer and pallisade parenchym were higher. Polyphenol content of resistant clones were higher but lignin and cellulose of both groups were similar. Chitinase activity which has a role in hydrolysis of mycelia cell wall was higher on the resistant clones, but peroxides which has a role in polymeration of lignin biosynthesis was similar between both groups. It is concluded that groups of terpene pinene, decane, myrcene, and octadecanoic acid, thickness of leaf epidermis, density and width of stomata pit, and chitinase activity plays important role in cocoa resistance to VSD. Key words: Theobroma cacaoL., clone, vascular-streak dieback, resistance, leaf

  11. Effect of Enzyme Inhibitors on Terpene Trilactones Biosynthesis and Gene Expression Profiling in Ginkgo biloba Cultured Cells.

    Science.gov (United States)

    Chen, Lijia; Tong, Hui; Wang, Mingxuan; Zhu, Jianhua; Zi, Jiachen; Song, Liyan; Yu, Rongmin

    2015-12-01

    The biosynthetic pathway of terpene trilactones of Ginkgo biloba is unclear. In this present study, suspension cultured cells of G. biloba were used to explore the regulation of the mevalonic acid (MVA) and methylerythritol 4-phosphate (MEP) pathways in response to specific enzyme inhibitors (lovastatin and clomazone). The results showed that the biosynthesis of bilobalide was more highly correlated with the MVA pathway, and the biosynthesis of ginkgolides was more highly correlated with the MEP pathway. Meanwhile, according to the results, it could be speculated that bilobalide might be a product of ginkgolide metabolism.

  12. Melanie Klein's metapsychology: phenomenological and mechanistic perspective.

    Science.gov (United States)

    Mackay, N

    1981-01-01

    Freud's metapsychology is the subject of an important debate. This is over whether psychoanalysis is best construed as a science of the natural science type or as a special human science. The same debate applies to Melanie Klein's work. In Klein's metapsychology are two different and incompatible models of explanation. One is taken over from Freud's structural theory and appears to be similarly mechanistic. The other is clinically based and phenomenological. These two are discussed with special reference to the concepts of "phantasy" and "internal object".

  13. Conceptualising population health: from mechanistic thinking to complexity science.

    Science.gov (United States)

    Jayasinghe, Saroj

    2011-01-20

    The mechanistic interpretation of reality can be traced to the influential work by René Descartes and Sir Isaac Newton. Their theories were able to accurately predict most physical phenomena relating to motion, optics and gravity. This paradigm had at least three principles and approaches: reductionism, linearity and hierarchy. These ideas appear to have influenced social scientists and the discourse on population health. In contrast, Complexity Science takes a more holistic view of systems. It views natural systems as being 'open', with fuzzy borders, constantly adapting to cope with pressures from the environment. These are called Complex Adaptive Systems (CAS). The sub-systems within it lack stable hierarchies, and the roles of agency keep changing. The interactions with the environment and among sub-systems are non-linear interactions and lead to self-organisation and emergent properties. Theoretical frameworks such as epi+demos+cracy and the ecosocial approach to health have implicitly used some of these concepts of interacting dynamic sub-systems. Using Complexity Science we can view population health outcomes as an emergent property of CAS, which has numerous dynamic non-linear interactions among its interconnected sub-systems or agents. In order to appreciate these sub-systems and determinants, one should acquire a basic knowledge of diverse disciplines and interact with experts from different disciplines. Strategies to improve health should be multi-pronged, and take into account the diversity of actors, determinants and contexts. The dynamic nature of the system requires that the interventions are constantly monitored to provide early feedback to a flexible system that takes quick corrections.

  14. Conceptualising population health: from mechanistic thinking to complexity science

    Directory of Open Access Journals (Sweden)

    Jayasinghe Saroj

    2011-01-01

    Full Text Available Abstract The mechanistic interpretation of reality can be traced to the influential work by René Descartes and Sir Isaac Newton. Their theories were able to accurately predict most physical phenomena relating to motion, optics and gravity. This paradigm had at least three principles and approaches: reductionism, linearity and hierarchy. These ideas appear to have influenced social scientists and the discourse on population health. In contrast, Complexity Science takes a more holistic view of systems. It views natural systems as being 'open', with fuzzy borders, constantly adapting to cope with pressures from the environment. These are called Complex Adaptive Systems (CAS. The sub-systems within it lack stable hierarchies, and the roles of agency keep changing. The interactions with the environment and among sub-systems are non-linear interactions and lead to self-organisation and emergent properties. Theoretical frameworks such as epi+demos+cracy and the ecosocial approach to health have implicitly used some of these concepts of interacting dynamic sub-systems. Using Complexity Science we can view population health outcomes as an emergent property of CAS, which has numerous dynamic non-linear interactions among its interconnected sub-systems or agents. In order to appreciate these sub-systems and determinants, one should acquire a basic knowledge of diverse disciplines and interact with experts from different disciplines. Strategies to improve health should be multi-pronged, and take into account the diversity of actors, determinants and contexts. The dynamic nature of the system requires that the interventions are constantly monitored to provide early feedback to a flexible system that takes quick corrections.

  15. Fuel swelling importance in PCI mechanistic modelling

    International Nuclear Information System (INIS)

    Arimescu, V.I.

    2005-01-01

    Under certain conditions, fuel pellet swelling is the most important factor in determining the intensity of the pellet-to-cladding mechanical interaction (PCMI). This is especially true during power ramps, which lead to a temperature increase to a higher terminal plateau that is maintained for hours. The time-dependent gaseous swelling is proportional to temperature and is also enhanced by the increased gas atom migration to the grain boundary during the power ramp. On the other hand, gaseous swelling is inhibited by a compressive hydrostatic stress in the pellet. Therefore, PCMI is the net result of combining gaseous swelling and pellet thermal expansion with the opposing feedback from the cladding mechanical reaction. The coupling of the thermal and mechanical processes, mentioned above, with various feedback loops is best simulated by a mechanistic fuel code. This paper discusses a mechanistic swelling model that is coupled with a fission gas release model as well as a mechanical model of the fuel pellet. The role of fuel swelling is demonstrated for typical power ramps at different burn-ups. Also, fuel swelling plays a significant role in avoiding the thermal instability for larger gap fuel rods, by limiting the potentially exponentially increasing gap due to the positive feedback loop effect of increasing fission gas release and the associated over-pressure inside the cladding. (author)

  16. Appropriateness of mechanistic and non-mechanistic models for the application of ultrafiltration to mixed waste

    International Nuclear Information System (INIS)

    Foust, Henry; Ghosehajra, Malay

    2007-01-01

    This study asks two questions: (1) How appropriate is the use of a basic filtration equation to the application of ultrafiltration of mixed waste, and (2) How appropriate are non-parametric models for permeate rates (volumes)? To answer these questions, mechanistic and non-mechanistic approaches are developed for permeate rates and volumes associated with an ultrafiltration/mixed waste system in dia-filtration mode. The mechanistic approach is based on a filtration equation which states that t/V vs. V is a linear relationship. The coefficients associated with this linear regression are composed of physical/chemical parameters of the system and based the mass balance equation associated with the membrane and associated developing cake layer. For several sets of data, a high correlation is shown that supports the assertion that t/V vs. V is a linear relationship. It is also shown that non-mechanistic approaches, i.e., the use of regression models to are not appropriate. One models considered is Q(p) = a*ln(Cb)+b. Regression models are inappropriate because the scale-up from a bench scale (pilot scale) study to full-scale for permeate rates (volumes) is not simply the ratio of the two membrane surface areas. (authors)

  17. Potential contribution of fish feed and phytoplankton to the content of volatile terpenes in cultured Pangasius (Pangasianodon hypophthalmus) and Tilapia (Oreochromis niloticus)

    DEFF Research Database (Denmark)

    Podduturi, Raju; Petersen, Mikael Agerlin; Mahmud, Sultan

    2017-01-01

    Geosmin and 2-methylisoborneol are the most recognized off-flavors in freshwater fish, but terpenes may also contribute off-flavor in fish. We identified six monoterpenes, 11 sesquiterpenes, and three terpene-related compounds in pangasius and tilapia from aquaculture farms in Bangladesh. The con...

  18. Conformational preference of a chiral terpene: vibrational circular dichroism (VCD), infrared and Raman study of S-(-)-limonene oxide.

    Science.gov (United States)

    Moreno, Juan Ramón Avilés; Ureña, Francisco Partal; González, Juan Jesús López

    2009-04-14

    S-(-)-Limonene oxide (4-isopropenyl-1-methyl-7-oxabicyclo[4.1.0]heptane) is a secondary metabolite and an atmospheric pollutant product of oxidation of other terpenes, such as limonene and alpha-pinene, among others. For the first time, a theoretical study of the molecular structure and a theoretical and experimental analysis of the infrared and Raman spectra of this chemical species are presented. Theoretical calculations reveal the existence of two conformers depending on the position of the isopropenyl group (axial and equatorial) and twelve rotamers (six equatorials and six axials), with the six equatorial ones as the most stable (around 97%) on the basis of Boltzmann's distribution law. In the current work, from a reliable assignment of the IR and Raman spectra and with the help from the study of the VCD spectrum of the title compound, five rotamers have been detected experimentally in the liquid phase. The present work reveals that IR, Raman and VCD are helpful complementary techniques to characterize flexible systems, as terpenes, which present several conformers.

  19. QCM-Arrays for Sensing Terpenes in Fresh and Dried Herbs via Bio-Mimetic MIP Layers †

    Science.gov (United States)

    Iqbal, Naseer; Mustafa, Ghulam; Rehman, Abdul; Biedermann, Alexander; Najafi, Bita; Lieberzeit, Peter A.; Dickert, Franz L.

    2010-01-01

    A piezoelectric 10 MHz multichannel quartz crystal microbalance (MQCM), coated with six molecularly imprinted polystyrene artificial recognition membranes have been developed for selective quantification of terpenes emanated from fresh and dried Lamiaceae family species, i.e., rosemary (Rosmarinus Officinalis L.), basil (Ocimum Basilicum) and sage (Salvia Officinalis). Optimal e-nose parameters, such as layer heights (1–6 KHz), sensitivity <20 ppm of analytes, selectivity at 50 ppm of terpenes, repeatability and reproducibility were thoroughly adjusted prior to online monitoring. Linearity in reversible responses over a wide concentration range <20–250 ppm has been achieved. Discrimination between molecules of similar molar masses, even for isomers, e.g. α-pinene and β-pinene is possible. The array has proven its sensitive and selective properties of sensor responses (20–1,200 Hz) for the difference of fresh and dried herbs. The sensor data attained was validated by GC-MS, to analyze the profiles of sensor emanation patterns. The shelf-life of herbs was monitored via emanation of organic volatiles during a few days. Such an array in association with data analysis tools can be utilized for characterizing complex mixtures. PMID:22163554

  20. Mechanistic investigations of the ethylene tetramerisation reaction.

    Science.gov (United States)

    Overett, Matthew J; Blann, Kevin; Bollmann, Annette; Dixon, John T; Haasbroek, Daleen; Killian, Esna; Maumela, Hulisani; McGuinness, David S; Morgan, David H

    2005-08-03

    The unprecedented selective tetramerisation of ethylene to 1-octene was recently reported. In the present study various mechanistic aspects of this novel transformation were investigated. The unusually high 1-octene selectivity in chromium-catalyzed ethylene tetramerisation reactions is caused by the unique extended metallacyclic mechanism in operation. Both 1-octene and higher 1-alkenes are formed by further ethylene insertion into a metallacycloheptane intermediate, whereas 1-hexene is formed by elimination from this species as in other reported trimerisation reactions. This is supported by deuterium labeling studies, analysis of the molar distribution of 1-alkene products, and identification of secondary co-oligomerization reaction products. In addition, the formation of two C6 cyclic products, methylenecyclopentane and methylcyclopentane, is discussed, and a bimetallic disproportionation mechanism to account for the available data is proposed.

  1. Bioavailability and Pharmacokinetics of Genistein: Mechanistic Studies on its ADME

    Science.gov (United States)

    Yang, Zhen; Kulkarni, Kaustubh; Zhu, Wei; Hu, Ming

    2014-01-01

    Genistein, one of the most active natural flavonoids, exerts various biological effects including chemoprevention, antioxidation, antiproliferation and anticancer. More than 30 clinical trials of genistein with various disease indications have been conducted to evaluate its clinical efficacy. Based on many animals and human pharmacokinetic studies, it is well known that the most challenge issue for developing genistein as a chemoprevention agent is the low oral bioavailability, which may be the major reason relating to its ambiguous therapeutic effects and large interindividual variations in clinical trials. In order to better correlate pharmacokinetic to pharmacodynamics results in animals and clinical studies, an in-depth understanding of pharmacokinetic behavior of genistein and its ADME properties are needed. Numerous in vitro/in vivo ADME studies had been conducted to reveal the main factors contributing to the low oral bioavailability of genistein. Therefore, this review focuses on summarizing the most recent progress on mechanistic studies of genistein ADME and provides a systemic view of these processes to explain genistein pharmacokinetic behaviors in vivo. The better understanding of genistein ADME property may lead to development of proper strategy to improve genistein oral bioavailability via mechanism-based approaches. PMID:22583407

  2. View relations

    DEFF Research Database (Denmark)

    Knudsen, Søren; Carpendale, Sheelagh

    2016-01-01

    In this paper, we explore the potential of using visual representations to support people in managing, organizing, and understanding relations between multiple visualization views. Multiple views can help people understand different facets of data and data processing, and are a crucial part of data...... analysis particularly when it is done collaboratively. Both the growing use of multiple views and the increasing display sizes have amplified the need to explore how to better help people to understand the relations between many views. To improve our understanding of how to visualize view relations, we...... invited visualization and interaction designers to critique and sketch representations of view relations. The participants provided design critiques, and sketched their own relation representations. Our findings expand the range and palette of ways of visually linking visualization views and suggest new...

  3. Volatile and within-needle terpene changes to Douglas-fir trees associated with Douglas-fir beetle (Coleoptera: Curculionidae) attack

    Science.gov (United States)

    A. D. Giunta; Justin Runyon; M. J. Jenkins; M. Teich

    2016-01-01

    Mass attack by tree-killing bark beetles (Curculionidae: Scolytinae) brings about large chemical changes in host trees that can have important ecological consequences. For example, mountain pine beetle (Dendroctonus ponderosae Hopkins) attack increases emission of terpenes by lodgepole pine (Pinus contorta Dougl. ex Loud.), affecting foliage flammability with...

  4. "Ratio via Machina": Three Standards of Mechanistic Explanation in Sociology

    Science.gov (United States)

    Aviles, Natalie B.; Reed, Isaac Ariail

    2017-01-01

    Recently, sociologists have expended much effort in attempts to define social mechanisms. We intervene in these debates by proposing that sociologists in fact have a choice to make between three standards of what constitutes a good mechanistic explanation: substantial, formal, and metaphorical mechanistic explanation. All three standards are…

  5. Advanced REACH Tool (ART) : Calibration of the mechanistic model

    NARCIS (Netherlands)

    Schinkel, J.; Warren, N.; Fransman, W.; Tongeren, M. van; McDonnell, P.; Voogd, E.; Cherrie, J.W.; Tischer, M.; Kromhout, H.; Tielemans, E.

    2011-01-01

    The mechanistic model of the Advanced Reach Tool (ART) provides a relative ranking of exposure levels from different scenarios. The objectives of the calibration described in this paper are threefold: to study whether the mechanistic model scores are accurately ranked in relation to exposure

  6. Mechanistic curiosity will not kill the Bayesian cat

    NARCIS (Netherlands)

    Borsboom, D.; Wagenmakers, E.-J.; Romeijn, J.-W.

    2011-01-01

    Jones & Love (J&L) suggest that Bayesian approaches to the explanation of human behavior should be constrained by mechanistic theories. We argue that their proposal misconstrues the relation between process models, such as the Bayesian model, and mechanisms. While mechanistic theories can answer

  7. Mechanistic curiosity will not kill the Bayesian cat

    NARCIS (Netherlands)

    Borsboom, Denny; Wagenmakers, Eric-Jan; Romeijn, Jan-Willem

    Jones & Love (J&L) suggest that Bayesian approaches to the explanation of human behavior should be constrained by mechanistic theories. We argue that their proposal misconstrues the relation between process models, such as the Bayesian model, and mechanisms. While mechanistic theories can answer

  8. Causation at Different Levels: Tracking the Commitments of Mechanistic Explanations

    DEFF Research Database (Denmark)

    Fazekas, Peter; Kertész, Gergely

    2011-01-01

    This paper tracks the commitments of mechanistic explanations focusing on the relation between activities at different levels. It is pointed out that the mechanistic approach is inherently committed to identifying causal connections at higher levels with causal connections at lower levels. For th...... their autonomy at the same time than standard reductive accounts are, and that what mechanistic explanations are able to do at best is showing that downward causation does not exist......., whereas, in a recent paper, Craver and Bechtel argue that the mechanistic approach is able to make downward causation intelligible. The paper concludes that the mechanistic approach imbued with identity statements is no better candidate for anchoring higher levels to lower ones while maintaining...

  9. The family of terpene synthases in plants: a mid-size family of genes for specialized metabolism that is highly diversified throughout the kingdom.

    Science.gov (United States)

    Chen, Feng; Tholl, Dorothea; Bohlmann, Jörg; Pichersky, Eran

    2011-04-01

    Some plant terpenes such as sterols and carotenes are part of primary metabolism and found essentially in all plants. However, the majority of the terpenes found in plants are classified as 'secondary' compounds, those chemicals whose synthesis has evolved in plants as a result of selection for increased fitness via better adaptation to the local ecological niche of each species. Thousands of such terpenes have been found in the plant kingdom, but each species is capable of synthesizing only a small fraction of this total. In plants, a family of terpene synthases (TPSs) is responsible for the synthesis of the various terpene molecules from two isomeric 5-carbon precursor 'building blocks', leading to 5-carbon isoprene, 10-carbon monoterpenes, 15-carbon sesquiterpenes and 20-carbon diterpenes. The bryophyte Physcomitrella patens has a single TPS gene, copalyl synthase/kaurene synthase (CPS/KS), encoding a bifunctional enzyme producing ent-kaurene, which is a precursor of gibberellins. The genome of the lycophyte Selaginella moellendorffii contains 18 TPS genes, and the genomes of some model angiosperms and gymnosperms contain 40-152 TPS genes, not all of them functional and most of the functional ones having lost activity in either the CPS- or KS-type domains. TPS genes are generally divided into seven clades, with some plant lineages having a majority of their TPS genes in one or two clades, indicating lineage-specific expansion of specific types of genes. Evolutionary plasticity is evident in the TPS family, with closely related enzymes differing in their product profiles, subcellular localization, or the in planta substrates they use. © 2011 The Authors. The Plant Journal © 2011 Blackwell Publishing Ltd.

  10. Toxic effects on and structure-toxicity relationships of phenylpropanoids, terpenes, and related compounds in Aedes aegypti larvae.

    Science.gov (United States)

    Santos, Sandra R L; Silva, Viviane B; Melo, Manuela A; Barbosa, Juliana D F; Santos, Roseli L C; de Sousa, Damião P; Cavalcanti, Sócrates C H

    2010-12-01

    In the search for toxic compounds against Aedes aegypti L. (Diptera: Culicidae) larvae, a collection of commercially available aromatic and aliphatic diversely substituted compounds were selected and evaluated. p-Cymene exhibited the highest larvicidal potency LC₅₀ = 51 ppm, whereas 1,8-cineole exhibited the lowest activity value LC₅₀ = 1419 ppm. To aid future work on the search for larvicidal compounds, the structure-toxicity relationships of this collection have been evaluated. The presence of lipophilic groups results in an overall increase in potency. In general, the presence of hydroxyl groups resulted in less potent compounds. However, methylation of such hydroxyls led to an overall increase in potency. The most potent compounds showed comparably good larvicidal activity in A. aegypti larvae as other terpenes, which we assume to be the result of the increased lipophilicity.

  11. Colophonium and Compositae mix as markers of fragrance allergy: cross-reactivity between fragrance terpenes, colophonium and compositae plant extracts

    DEFF Research Database (Denmark)

    Paulsen, Evy; Andersen, Klaus Ejner

    2005-01-01

    The aim of this study was to assess the strength of any association between sensitization to 'new' fragrance compounds and sensitization to Compositae, fragrance mix, Myroxylon pereirae resin and colophonium, respectively. Consecutive eczema patients were tested with a series of essential oils...... and selected fragrance compounds and another series of oxidized terpenes in connection with European multicentre fragrance projects. Contact allergy to either series was frequently detected, in 5% of 318 and 4.6% of 262 persons tested, and both had a statistically significant association with Compositae......, colophonium and fragrance mix sensitization. The individual results indicated that simultaneously occurring positive reactions to essential oils, colophonium and Compositae were based on cross-reactivity rather than concomitant sensitization. Thus, all patients with positive reaction to the rare fragrance...

  12. Mechanistic movement models to understand epidemic spread.

    Science.gov (United States)

    Fofana, Abdou Moutalab; Hurford, Amy

    2017-05-05

    An overlooked aspect of disease ecology is considering how and why animals come into contact with one and other resulting in disease transmission. Mathematical models of disease spread frequently assume mass-action transmission, justified by stating that susceptible and infectious hosts mix readily, and foregoing any detailed description of host movement. Numerous recent studies have recorded, analysed and modelled animal movement. These movement models describe how animals move with respect to resources, conspecifics and previous movement directions and have been used to understand the conditions for the occurrence and the spread of infectious diseases when hosts perform a type of movement. Here, we summarize the effect of the different types of movement on the threshold conditions for disease spread. We identify gaps in the literature and suggest several promising directions for future research. The mechanistic inclusion of movement in epidemic models may be beneficial for the following two reasons. Firstly, the estimation of the transmission coefficient in an epidemic model is possible because animal movement data can be used to estimate the rate of contacts between conspecifics. Secondly, unsuccessful transmission events, where a susceptible host contacts an infectious host but does not become infected can be quantified. Following an outbreak, this enables disease ecologists to identify 'near misses' and to explore possible alternative epidemic outcomes given shifts in ecological or immunological parameters.This article is part of the themed issue 'Opening the black box: re-examining the ecology and evolution of parasite transmission'. © 2017 The Author(s).

  13. Mechanistic Basis of Cocrystal Dissolution Advantage.

    Science.gov (United States)

    Cao, Fengjuan; Amidon, Gordon L; Rodríguez-Hornedo, Naír; Amidon, Gregory E

    2018-01-01

    Current interest in cocrystal development resides in the advantages that the cocrystal may have in solubility and dissolution compared with the parent drug. This work provides a mechanistic analysis and comparison of the dissolution behavior of carbamazepine (CBZ) and its 2 cocrystals, carbamazepine-saccharin (CBZ-SAC) and carbamazepine-salicylic acid (CBZ-SLC) under the influence of pH and micellar solubilization. A simple mathematical equation is derived based on the mass transport analyses to describe the dissolution advantage of cocrystals. The dissolution advantage is the ratio of the cocrystal flux to drug flux and is defined as the solubility advantage (cocrystal to drug solubility ratio) times the diffusivity advantage (cocrystal to drug diffusivity ratio). In this work, the effective diffusivity of CBZ in the presence of surfactant was determined to be different and less than those of the cocrystals. The higher effective diffusivity of drug from the dissolved cocrystals, the diffusivity advantage, can impart a dissolution advantage to cocrystals with lower solubility than the parent drug while still maintaining thermodynamic stability. Dissolution conditions where cocrystals can display both thermodynamic stability and a dissolution advantage can be obtained from the mass transport models, and this information is useful for both cocrystal selection and formulation development. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  14. Mechanistic insights into type III restriction enzymes.

    Science.gov (United States)

    Raghavendra, Nidhanapati K; Bheemanaik, Shivakumara; Rao, Desirazu N

    2012-01-01

    Type III restriction-modification (R-M) enzymes need to interact with two separate unmethylated DNA sequences in indirectly repeated, head-to-head orientations for efficient cleavage to occur at a defined location next to only one of the two sites. However, cleavage of sites that are not in head-to-head orientation have been observed to occur under certain reaction conditions in vitro. ATP hydrolysis is required for the long-distance communication between the sites prior to cleavage. Type III R-M enzymes comprise two subunits, Res and Mod that form a homodimeric Mod2 and a heterotetrameric Res2Mod2 complex. The Mod subunit in M2 or R2M2 complex recognizes and methylates DNA while the Res subunit in R2M2 complex is responsible for ATP hydrolysis, DNA translocation and cleavage. A vast majority of biochemical studies on Type III R-M enzymes have been undertaken using two closely related enzymes, EcoP1I and EcoP15I. Divergent opinions about how the long-distance interaction between the recognition sites exist and at least three mechanistic models based on 1D- diffusion and/or 3D- DNA looping have been proposed.

  15. Mechanistic niche modelling: combining physiological and spatial data to predict species' ranges.

    Science.gov (United States)

    Kearney, Michael; Porter, Warren

    2009-04-01

    Species distribution models (SDMs) use spatial environmental data to make inferences on species' range limits and habitat suitability. Conceptually, these models aim to determine and map components of a species' ecological niche through space and time, and they have become important tools in pure and applied ecology and evolutionary biology. Most approaches are correlative in that they statistically link spatial data to species distribution records. An alternative strategy is to explicitly incorporate the mechanistic links between the functional traits of organisms and their environments into SDMs. Here, we review how the principles of biophysical ecology can be used to link spatial data to the physiological responses and constraints of organisms. This provides a mechanistic view of the fundamental niche which can then be mapped to the landscape to infer range constraints. We show how physiologically based SDMs can be developed for different organisms in different environmental contexts. Mechanistic SDMs have different strengths and weaknesses to correlative approaches, and there are many exciting and unexplored prospects for integrating the two approaches. As physiological knowledge becomes better integrated into SDMs, we will make more robust predictions of range shifts in novel or non-equilibrium contexts such as invasions, translocations, climate change and evolutionary shifts.

  16. Identifying mechanistic similarities in drug responses

    KAUST Repository

    Zhao, C.

    2012-05-15

    Motivation: In early drug development, it would be beneficial to be able to identify those dynamic patterns of gene response that indicate that drugs targeting a particular gene will be likely or not to elicit the desired response. One approach would be to quantitate the degree of similarity between the responses that cells show when exposed to drugs, so that consistencies in the regulation of cellular response processes that produce success or failure can be more readily identified.Results: We track drug response using fluorescent proteins as transcription activity reporters. Our basic assumption is that drugs inducing very similar alteration in transcriptional regulation will produce similar temporal trajectories on many of the reporter proteins and hence be identified as having similarities in their mechanisms of action (MOA). The main body of this work is devoted to characterizing similarity in temporal trajectories/signals. To do so, we must first identify the key points that determine mechanistic similarity between two drug responses. Directly comparing points on the two signals is unrealistic, as it cannot handle delays and speed variations on the time axis. Hence, to capture the similarities between reporter responses, we develop an alignment algorithm that is robust to noise, time delays and is able to find all the contiguous parts of signals centered about a core alignment (reflecting a core mechanism in drug response). Applying the proposed algorithm to a range of real drug experiments shows that the result agrees well with the prior drug MOA knowledge. © The Author 2012. Published by Oxford University Press. All rights reserved.

  17. Kinetic, mechanistic and spectral investigation of ruthenium (III ...

    Indian Academy of Sciences (India)

    Unknown

    Kinetic, mechanistic and spectral investigation of ruthenium (III)- catalysed oxidation of atenolol by alkaline permanganate. (stopped-flow technique). RAHAMATALLA M MULLA, GURUBASAVARAJ C HIREMATH and. SHARANAPPA T NANDIBEWOOR*. PG Department of Studies in Chemistry, Karnatak University, ...

  18. Investigation of mechanistic deterioration modeling for bridge design and management.

    Science.gov (United States)

    2017-04-01

    The ongoing deterioration of highway bridges in Colorado dictates that an effective method for allocating limited management resources be developed. In order to predict bridge deterioration in advance, mechanistic models that analyze the physical pro...

  19. AASHTO mechanistic-empirical pavement design guide parametric study.

    Science.gov (United States)

    2012-03-01

    This study focuses on assessing the robustness of the AASHTO Mechanistic-Empirical Pavement Design Guide (MEPDG v 1.1) for rigid pavement : design projects in Wisconsin. The primary tasks conducted in this study included performing sensitivity analys...

  20. Overview of the South African mechanistic pavement design analysis method

    CSIR Research Space (South Africa)

    Theyse, HL

    1996-01-01

    Full Text Available A historical overview of the South African mechanistic pavement design method, from its development in the early 1970s to the present, is presented. Material characterization, structural analysis, and pavement life prediction are discussed...

  1. Mechanistic mathematical models: An underused platform for HPV research.

    Science.gov (United States)

    Ryser, Marc D; Gravitt, Patti E; Myers, Evan R

    2017-06-01

    Health economic modeling has become an invaluable methodology for the design and evaluation of clinical and public health interventions against the human papillomavirus (HPV) and associated diseases. At the same time, relatively little attention has been paid to a different yet complementary class of models, namely that of mechanistic mathematical models. The primary focus of mechanistic mathematical models is to better understand the intricate biologic mechanisms and dynamics of disease. Inspired by a long and successful history of mechanistic modeling in other biomedical fields, we highlight several areas of HPV research where mechanistic models have the potential to advance the field. We argue that by building quantitative bridges between biologic mechanism and population level data, mechanistic mathematical models provide a unique platform to enable collaborations between experimentalists who collect data at different physical scales of the HPV infection process. Through such collaborations, mechanistic mathematical models can accelerate and enhance the investigation of HPV and related diseases. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  2. Systemic and cerebral exposure to and pharmacokinetics of flavonols and terpene lactones after dosing standardized Ginkgo biloba leaf extracts to rats via different routes of administration.

    Science.gov (United States)

    Chen, Feng; Li, Li; Xu, Fang; Sun, Yan; Du, Feifei; Ma, Xutao; Zhong, Chenchun; Li, Xiuxue; Wang, Fengqing; Zhang, Nating; Li, Chuan

    2013-09-01

    Flavonols and terpene lactones are putatively responsible for the properties of Ginkgo biloba leaf extracts that relate to prevention and treatment of cardiovascular disease and cerebral insufficiency. Here, we characterized rat systemic and cerebral exposure to these ginkgo compounds after dosing, as well as the compounds' pharmacokinetics. Rats received single or multiple doses of ShuXueNing injection (prepared from GBE50 for intravenous administration) or GBE50 (a standardized extract of G. biloba leaves for oral administration). Brain delivery of the ginkgo compounds was assessed with microdialysis. Various rat samples were analysed using liquid chromatography/mass spectrometry. Slow terminal elimination features of the flavonols counterbalanced the influence of poor oral bioavailability on their systemic exposure levels, which also resulted in significant accumulation of the compounds in plasma during the subchronic treatment with ShuXueNing injection and GBE50. Unlike the flavonols, the terpene lactones had poor enterohepatic circulation due to their rapid renal excretion and unknown metabolism. The flavonol glycosides occurred as major forms in plasma after dosing with ShuXueNing injection, while the flavonol aglycone conjugates were predominant in plasma after dosing with GBE50. Cerebral exposure was negligible for the flavonols and low for the terpene lactones. Unlike the significant systemic exposure levels, the levels of cerebral exposure to the flavonols and terpene lactones are low. The elimination kinetic differences between the two classes of ginkgo compounds influence their relative systemic exposure levels. The information gained is relevant to linking ginkgo administration to the medicinal effects. © 2013 The Authors. British Journal of Pharmacology published by John Wiley &. Sons Ltd on behalf of The British Pharmacological Society.

  3. Systemic and cerebral exposure to and pharmacokinetics of flavonols and terpene lactones after dosing standardized Ginkgo biloba leaf extracts to rats via different routes of administration

    Science.gov (United States)

    Chen, Feng; Li, Li; Xu, Fang; Sun, Yan; Du, Feifei; Ma, Xutao; Zhong, Chenchun; Li, Xiuxue; Wang, Fengqing; Zhang, Nating; Li, Chuan

    2013-01-01

    BACKGROUND AND PURPOSE Flavonols and terpene lactones are putatively responsible for the properties of Ginkgo biloba leaf extracts that relate to prevention and treatment of cardiovascular disease and cerebral insufficiency. Here, we characterized rat systemic and cerebral exposure to these ginkgo compounds after dosing, as well as the compounds’ pharmacokinetics. EXPERIMENTAL APPROACH Rats received single or multiple doses of ShuXueNing injection (prepared from GBE50 for intravenous administration) or GBE50 (a standardized extract of G. biloba leaves for oral administration). Brain delivery of the ginkgo compounds was assessed with microdialysis. Various rat samples were analysed using liquid chromatography/mass spectrometry. KEY RESULTS Slow terminal elimination features of the flavonols counterbalanced the influence of poor oral bioavailability on their systemic exposure levels, which also resulted in significant accumulation of the compounds in plasma during the subchronic treatment with ShuXueNing injection and GBE50. Unlike the flavonols, the terpene lactones had poor enterohepatic circulation due to their rapid renal excretion and unknown metabolism. The flavonol glycosides occurred as major forms in plasma after dosing with ShuXueNing injection, while the flavonol aglycone conjugates were predominant in plasma after dosing with GBE50. Cerebral exposure was negligible for the flavonols and low for the terpene lactones. CONCLUSION AND IMPLICATIONS Unlike the significant systemic exposure levels, the levels of cerebral exposure to the flavonols and terpene lactones are low. The elimination kinetic differences between the two classes of ginkgo compounds influence their relative systemic exposure levels. The information gained is relevant to linking ginkgo administration to the medicinal effects. PMID:23808355

  4. MECHANISTIC STUDIES OF IMPROVED FOAM EOR PROCESSES

    Energy Technology Data Exchange (ETDEWEB)

    William R. Rossen

    2003-03-31

    . We find that such behavior is consistent with earlier models of foam viscosity in tubes, and a modified model for the low-quality regime can account for this behavior. It is not yet clear why this new regime appears in some cases and not in others. Simple modeling suggests that the answer may have to do with the sensitivity of gas trapping to pressure gradient. Research on Task 3 continued to focus on foam generation at limited pressure gradient in sandpacks. We investigated the effects of permeability, surfactant concentration and liquid injection rates on foam generation. In addition, a careful review of published studies showed that repeated snap-off is not a plausible mechanism of foam generation in homogeneous porous media beyond the stage of initial drainage from a fully liquid-saturated state. Snap-off has been the focus of much research on foam generation and is incorporated into most mechanistic foam simulators. This finding should force a reconsideration of its role in foam generation and properties in porous media.

  5. Mechanistic Insights into Reprogramming to Induced Pluripotency

    Science.gov (United States)

    Ho, Ritchie; Chronis, Constantinos; Plath, Kathrin

    2010-01-01

    Induced pluripotent stem (iPS) cells can be generated from various embryonic or adult cell types upon expression of a set of few transcription factors, most commonly consisting of Oct4, Sox2, c-Myc and Klf4, following a strategy originally published by Takahashi and Yamanaka in 2006 (Takahashi and Yamanaka, 2006). Since iPS cells are molecularly and functionally similar to embryonic stem (ES) cells, they provide a source of patient-specific pluripotent cells for regenerative medicine and disease modeling, and therefore have generated enormous scientific and public interest. The generation of iPS cells also presents a powerful tool for dissecting mechanisms that stabilize the differentiated state and are required for the establishment of pluripotency. In this review, we discuss our current view of the molecular mechanisms underlying transcription factor-mediated reprogramming to induced pluripotency. PMID:20945378

  6. Acaricidal Potentials of the Terpene-rich Essential Oils of Two Iranian Eucalyptus Species against Tetranychus urticae Koch.

    Science.gov (United States)

    Ebadollahi, Asgar; Sendi, Jalal Jalali; Maroufpoor, Mostafa; Rahimi-Nasrabadi, Mehdi

    2017-03-01

    There is a rapid growth in the screening of plant materials for finding new bio-pesticides. In the present study, the essential oils of E. oleosa and E. torquata leaves were extracted using a Clevenger apparatus and their chemical profiles were investigated by Gas Chromatography-Mass Spectrometry (GC-MS). Among identified compounds, the terpenes had highest amount for both essential oils; 93.59% for E. oleosa and 97.69% for E. torquata. 1,8-Cineole (31.96%), α-pinene (15.25%) and trans-anethole (7.32%) in the essential oil of E. oleosa and 1,8-cineole (28.57%), α-pinene (15.74%) and globulol (13.11%) in the E. torquata essential oil were identified as the main components. The acaricidal activity of the essential oils of E. oleosa and E. torquata were examined using fumigation methods against the adult females of Tetranychus urticae Koch. The essential oils have potential acaricidal effects on T. urticae. The essential oil of E. oleosa with LC 50 value of 2.42 µL/L air was stronger than E. torquata. A correlation between log concentration and mite mortality has been observed. Based on the results of present study, it can be stated that the essential oils of E. oleosa and E. torquata have a worthy potential in the management of T. urticae.

  7. In Vitro Cytotoxic Potential of Essential Oils of Eucalyptus benthamii and Its Related Terpenes on Tumor Cell Lines

    Science.gov (United States)

    Döll-Boscardin, Patrícia Mathias; Sartoratto, Adilson; Sales Maia, Beatriz Helena Lameiro de Noronha; Padilha de Paula, Josiane; Nakashima, Tomoe; Farago, Paulo Vitor; Kanunfre, Carla Cristine

    2012-01-01

    Eucalyptus L. is traditionally used for many medicinal purposes. In particular, some Eucalyptus species have currently shown cytotoxic properties. Local Brazilian communities have used leaves of E. benthamii as a herbal remedy for various diseases, including cancer. Considering the lack of available data for supporting this cytotoxic effect, the goal of this paper was to study the in vitro cytotoxic potential of the essential oils from young and adult leaves of E. benthamii and some related terpenes (α-pinene, terpinen-4-ol, and γ-terpinene) on Jurkat, J774A.1 and HeLa cells lines. Regarding the cytotoxic activity based on MTT assay, the essential oils showed improved results than α-pinene and γ-terpinene, particularly for Jurkat and HeLa cell lines. Terpinen-4-ol revealed a cytotoxic effect against Jurkat cells similar to that observed for volatile oils. The results of LDH activity indicated that cytotoxic activity of samples against Jurkat cells probably involved cell death by apoptosis. The decrease of cell DNA content was demonstrated due to inhibition of Jurkat cells proliferation by samples as a result of cytotoxicity. In general, the essential oils from young and adult leaves of E. benthamii presented cytotoxicity against the investigated tumor cell lines which confirms their antitumor potential. PMID:22645627

  8. [Advances in metabolic engineering for the microbial production of naturally occurring terpenes-limonene and bisabolene: a mini review].

    Science.gov (United States)

    Pang, Yaru; Hu, Zhihui; Xiao, Dongguang; Yu, Aiqun

    2018-01-25

    Limonene (C₁₀H₁₆) and bisabolene (C₁₅H₂₄) are both naturally occurring terpenes in plants. Depending on the number of C₅ units, limonene and bisabolene are recognized as representative monoterpenes and sesquiterpenes, respectively. Limonene and bisabolene are important pharmaceutical and nutraceutical products used in the prevention and treatment of cancer and many other diseases. In addition, they can be used as starting materials to produce a range of commercially valuable products, such as pharmaceuticals, nutraceuticals, cosmetics, and biofuels. The low abundance or yield of limonene and bisabolene in plants renders their isolation from plant sources non-economically viable. Isolation of limonene and bisabolene from plants also suffers from low efficiency and often requires harsh reaction conditions, prolonged reaction times, and expensive equipment cost. Recently, the rapid developments in metabolic engineering of microbes provide a promising alternative route for producing these plant natural products. Therefore, producing limonene and bisabolene by engineering microbial cells into microbial factories is becoming an attractive alternative approach that can overcome the bottlenecks, making it more sustainable, environmentally friendly and economically competitive. Here, we reviewed the status of metabolic engineering of microbes that produce limonene and bisabolene including microbial hosts, key enzymes, metabolic pathways and engineering of limonene/bisabolene biosynthesis. Furthermore, key challenges and future perspectives were discussed.

  9. Measurements of secondary organic aerosol from oxidation of cycloalkenes, terpenes, and m-xylene using an Aerodyne aerosol mass spectrometer.

    Science.gov (United States)

    Bahreini, R; Keywood, M D; Ng, N L; Varutbangkul, V; Gao, S; Flagan, R C; Seinfeld, J H; Worsnop, D R; Jimenez, J L

    2005-08-01

    The Aerodyne aerosol mass spectrometer (AMS) was used to characterize physical and chemical properties of secondary organic aerosol (SOA) formed during ozonolysis of cycloalkenes and biogenic hydrocarbons and photo-oxidation of m-xylene. Comparison of mass and volume distributions from the AMS and differential mobility analyzers yielded estimates of "effective" density of the SOA in the range of 0.64-1.45 g/cm3, depending on the particular system. Increased contribution of the fragment at m/z 44, C02+ ion fragment of oxygenated organics, and higher "delta" values, based on ion series analysis of the mass spectra, in nucleation experiments of cycloalkenes suggest greater contribution of more oxygenated molecules to the SOA as compared to those formed under seeded experiments. Dominant negative "delta" values of SOA formed during ozonolysis of biogenics indicates the presence of terpene derivative structures or cyclic or unsaturated oxygenated compounds in the SOA. Evidence of acid-catalyzed heterogeneous chemistry, characterized by greater contribution of higher molecular weight fragments to the SOA and corresponding changes in "delta" patterns, is observed in the ozonolysis of alpha-pinene. Mass spectra of SOA formed during photooxidation of m-xylene exhibit features consistent with the presence of furandione compounds and nitro organics. This study demonstrates that mixtures of SOA compounds produced from similar precursors result in broadly similar AMS mass spectra. Thus, fragmentation patterns observed for biogenic versus anthropogenic SOA may be useful in determining the sources of ambient SOA.

  10. Variation of volatile terpenes in the edible fungi mycelia Flammulina velutipes and communications in fungus-mite interactions.

    Science.gov (United States)

    Li, Hui-Ping; Yang, Wen-Jian; Qu, Shao-Xuan; Pei, Fei; Luo, Xin; Mariga, Alfred Mugambi; Ma, Lin

    2018-01-01

    Many mites rely on fungi for nutrients, and fungi benefit from them with regard to spore dispersal, or nutrient resources. The interactions among mites and fungi are still not clear in most cases. This study analyzed volatile natural products from the liquid and solid cultures of the edible fungi, Flammulina velutipes (Fr.) Sing, and the solid mycelia induced by the storage mite, Tyrophagus putrescentiae Schrank, using HS-SPME-GC-MS/MS. Five new monoterpenes and 30 new sesquiterpenes were isolated from the two cultures of F. velutipes and a newly monoterpene and 14 newly sesquiterpenes found in the solid mycelia induced by the storage mite. Sesquiterpenes were abundant in the mycelial stage of F. velutipe. The mite was attracted by some volatiles from host fungi, dihydrocarveol, cedrol, β-caryophyllene, α-terpilene, β-pinene and benzaldehyde, analyzed by four-arm olfactometer. Some terpenes induced by T. putrescentiae, such as caryophyllene oxide, bicyclogermacrene, and (-)-spathulenol, would have potential biological function. These results suggest that some volatile sesquiterpenes play an important role in enabling the mite to recognize host fungi. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Measurements of acetone yields from the OH-initiated oxidation of terpenes by proton-transfer-reaction mass spectrometry

    International Nuclear Information System (INIS)

    Wisthaler, A.; Lindinger, W.; Jensen, N.R.; Winterhalter, R.; Hjorth, J.

    2002-01-01

    Biogenic VOCs (Volatile Organic Compounds) are known to be emitted in large quantities from vegetation exceeding largely global emissions of anthropogenic VOCs. Monoterpenes (C 10 H 16 ) are important constituents of biogenic VOC emissions. The atmospheric oxidation of Monoterpenes appears to be a potentially relevant source of acetone in the atmosphere. Acetone is present as a significant trace gas in the whole troposphere and influences in particular the atmospheric chemistry in the upper troposphere by substantially contributing to the formation of HO x radicals and peroxyacetyl nitrate (PAN). Acetone is formed promptly, following attack by the OH-radical on the terpene, via a series of highly unstable radical intermediates, but it is also formed slowly via the degradation of stable non-radical intermediates such as pinonaldehyde and nopinone. In order to investigate the relative importance of these processes, the OH-initiated oxidation of α-pinene and β-pinene was investigated in a chamber study, where the concentrations of monoterpenes, acetone, pinonaldehyde and nopinone were monitored by proton-transfer-reaction mass spectrometry (PTR-MS). It was found that significant amounts of acetone are formed directly, whenα-pinene and β-pinene are oxidized by the OH radical, but also secondary chemistry (degradation of primary reaction products) gives a significant contribution to the formation of acetone from monoterpenes. It can be concluded that atmospheric oxidation of monoterpenes contributes a significant fraction to the global acetone source strength. (nevyjel)

  12. Zograscopic viewing

    NARCIS (Netherlands)

    Koenderink, J.; Wijntjes, M.; Van Doorn, A.

    2013-01-01

    The “zograscope” is a “visual aid” (commonly known as “optical machine” in the 18th century) invented in the mid-18th century, and in general use until the early 20th century. It was intended to view single pictures (thus not stereographic pairs) with both eyes. The optics approximately eliminates

  13. Treatment of depression with low-strength transcranial pulsed electromagnetic fields : A mechanistic point of view

    NARCIS (Netherlands)

    van Belkum, S. M.; Bosker, F. J.; Kortekaas, R.; Beersma, D. G. M.; Schoevers, R. A.

    2016-01-01

    Background: Mood disorders constitute a high burden for both patients and society. Notwithstanding the large arsenal of available treatment options, a considerable group of patients does not remit on current antidepressant treatment. There is an urgent need to develop alternative treatment

  14. Silver nanoparticles: A new view on mechanistic aspects on antimicrobial activity.

    Science.gov (United States)

    Durán, Nelson; Durán, Marcela; de Jesus, Marcelo Bispo; Seabra, Amedea B; Fávaro, Wagner J; Nakazato, Gerson

    2016-04-01

    Silver nanoparticles are well known potent antimicrobial agents. Although significant progresses have been achieved on the elucidation of antimicrobial mechanism of silver nanoparticles, the exact mechanism of action is still not completely known. This overview incorporates a retrospective of previous reviews published and recent original contributions on the progress of research on antimicrobial mechanisms of silver nanoparticles. The main topics discussed include release of silver nanoparticles and silver ions, cell membrane damage, DNA interaction, free radical generation, bacterial resistance and the relationship of resistance to silver ions versus resistance to silver nanoparticles. The focus of the overview is to summarize the current knowledge in the field of antibacterial activity of silver nanoparticles. The possibility that pathogenic microbes may develop resistance to silver nanoparticles is also discussed. Antibacterial effect of nanoscopic silver generated a lot of interest both in research projects and in practical applications. However, the exact mechanism is still will have to be elucidated. This overview incorporates a retrospective of previous reviews published from 2007 to 2013 and recent original contributions on the progress of research on antimicrobial mechanisms to summarize our current knowledge in the field of antibacterial activity of silver nanoparticles. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Free will and punishment: A mechanistic view of human nature reduces retribution

    NARCIS (Netherlands)

    Sharrif, A.F.; Greene, J.D.; Karremans, J.C.; Luguri, J.B.; Clark, C.J.; Schooler, J.W.; Baumeister, R.F.; Vohs, K. D.

    2014-01-01

    If free-will beliefs support attributions of moral responsibility, then reducing these beliefs should make people less retributive in their attitudes about punishment. Four studies tested this prediction using both measured and manipulated free-will beliefs. Study 1 found that people with weaker

  16. Free will and punishment: a mechanistic view of human nature reduces retribution.

    Science.gov (United States)

    Shariff, Azim F; Greene, Joshua D; Karremans, Johan C; Luguri, Jamie B; Clark, Cory J; Schooler, Jonathan W; Baumeister, Roy F; Vohs, Kathleen D

    2014-08-01

    If free-will beliefs support attributions of moral responsibility, then reducing these beliefs should make people less retributive in their attitudes about punishment. Four studies tested this prediction using both measured and manipulated free-will beliefs. Study 1 found that people with weaker free-will beliefs endorsed less retributive, but not consequentialist, attitudes regarding punishment of criminals. Subsequent studies showed that learning about the neural bases of human behavior, through either lab-based manipulations or attendance at an undergraduate neuroscience course, reduced people's support for retributive punishment (Studies 2-4). These results illustrate that exposure to debates about free will and to scientific research on the neural basis of behavior may have consequences for attributions of moral responsibility. © The Author(s) 2014.

  17. Predicting interactions from mechanistic information: Can omic data validate theories?

    International Nuclear Information System (INIS)

    Borgert, Christopher J.

    2007-01-01

    To address the most pressing and relevant issues for improving mixture risk assessment, researchers must first recognize that risk assessment is driven by both regulatory requirements and scientific research, and that regulatory concerns may expand beyond the purely scientific interests of researchers. Concepts of 'mode of action' and 'mechanism of action' are used in particular ways within the regulatory arena, depending on the specific assessment goals. The data requirements for delineating a mode of action and predicting interactive toxicity in mixtures are not well defined from a scientific standpoint due largely to inherent difficulties in testing certain underlying assumptions. Understanding the regulatory perspective on mechanistic concepts will be important for designing experiments that can be interpreted clearly and applied in risk assessments without undue reliance on extrapolation and assumption. In like fashion, regulators and risk assessors can be better equipped to apply mechanistic data if the concepts underlying mechanistic research and the limitations that must be placed on interpretation of mechanistic data are understood. This will be critically important for applying new technologies to risk assessment, such as functional genomics, proteomics, and metabolomics. It will be essential not only for risk assessors to become conversant with the language and concepts of mechanistic research, including new omic technologies, but also, for researchers to become more intimately familiar with the challenges and needs of risk assessment

  18. Zograscopic viewing.

    Science.gov (United States)

    Koenderink, Jan; Wijntjes, Maarten; van Doorn, Andrea

    2013-01-01

    The "zograscope" is a "visual aid" (commonly known as "optical machine" in the 18th century) invented in the mid-18th century, and in general use until the early 20th century. It was intended to view single pictures (thus not stereographic pairs) with both eyes. The optics approximately eliminates the physiological cues (binocular disparity, vergence, accommodation, movement parallax, and image blur) that might indicate the flatness of the picture surface. The spatial structure of pictorial space is due to the remaining pictorial cues. As a consequence, many (or perhaps most) observers are aware of a heightened "plasticity" of the pictorial content for zograscopic as compared with natural viewing. We discuss the optics of the zograscope in some detail. Such an analysis is not available in the literature, whereas common "explanations" of the apparatus are evidently nonsensical. We constructed a zograscope, using modern parts, and present psychophysical data on its performance.

  19. Managing mechanistic and organic structure in health care organizations.

    Science.gov (United States)

    Olden, Peter C

    2012-01-01

    Managers at all levels in a health care organization must organize work to achieve the organization's mission and goals. This requires managers to decide the organization structure, which involves dividing the work among jobs and departments and then coordinating them all toward the common purpose. Organization structure, which is reflected in an organization chart, may range on a continuum from very mechanistic to very organic. Managers must decide how mechanistic versus how organic to make the entire organization and each of its departments. To do this, managers should carefully consider 5 factors for the organization and for each individual department: external environment, goals, work production, size, and culture. Some factors may push toward more mechanistic structure, whereas others may push in the opposite direction toward more organic structure. Practical advice can help managers at all levels design appropriate structure for their departments and organization.

  20. Functional characterization of nine Norway Spruce TPS genes and evolution of gymnosperm terpene synthases of the TPS-d subfamily.

    Science.gov (United States)

    Martin, Diane M; Fäldt, Jenny; Bohlmann, Jörg

    2004-08-01

    Constitutive and induced terpenoids are important defense compounds for many plants against potential herbivores and pathogens. In Norway spruce (Picea abies L. Karst), treatment with methyl jasmonate induces complex chemical and biochemical terpenoid defense responses associated with traumatic resin duct development in stems and volatile terpenoid emissions in needles. The cloning of (+)-3-carene synthase was the first step in characterizing this system at the molecular genetic level. Here we report the isolation and functional characterization of nine additional terpene synthase (TPS) cDNAs from Norway spruce. These cDNAs encode four monoterpene synthases, myrcene synthase, (-)-limonene synthase, (-)-alpha/beta-pinene synthase, and (-)-linalool synthase; three sesquiterpene synthases, longifolene synthase, E,E-alpha-farnesene synthase, and E-alpha-bisabolene synthase; and two diterpene synthases, isopimara-7,15-diene synthase and levopimaradiene/abietadiene synthase, each with a unique product profile. To our knowledge, genes encoding isopimara-7,15-diene synthase and longifolene synthase have not been previously described, and this linalool synthase is the first described from a gymnosperm. These functionally diverse TPS account for much of the structural diversity of constitutive and methyl jasmonate-induced terpenoids in foliage, xylem, bark, and volatile emissions from needles of Norway spruce. Phylogenetic analyses based on the inclusion of these TPS into the TPS-d subfamily revealed that functional specialization of conifer TPS occurred before speciation of Pinaceae. Furthermore, based on TPS enclaves created by distinct branching patterns, the TPS-d subfamily is divided into three groups according to sequence similarities and functional assessment. Similarities of TPS evolution in angiosperms and modeling of TPS protein structures are discussed.

  1. The volatile profiles of a rare apple (Malus domestica Borkh.) honey: shikimic acid-pathway derivatives, terpenes, and others.

    Science.gov (United States)

    Kuś, Piotr Marek; Jerković, Igor; Tuberoso, Carlo Ignazio Giovanni; Šarolić, Mladenka

    2013-09-01

    The volatile profiles of rare Malus domestica Borkh. honey were investigated for the first time. Two representative samples from Poland (sample I) and Spain (sample II) were selected by pollen analysis (44-45% of Malus spp. pollen) and investigated by GC/FID/MS after headspace solid-phase microextraction (HS-SPME) and ultrasonic solvent extraction (USE). The apple honey is characterized by high percentage of shikimic acid-pathway derivatives, as well as terpenes, norisoprenoids, and some other compounds such as coumaran and methyl 1H-indole-3-acetate. The main compounds of the honey headspace were (sample I; sample II): benzaldehyde (9.4%; 32.1%), benzyl alcohol (0.3%; 14.4%), hotrienol (26.0%, 6.2%), and lilac aldehyde isomers (26.3%; 1.7%), but only Spanish sample contained car-2-en-4-one (10.2%). CH2 Cl2 and pentane/Et2 O 1 : 2 (v/v) were used for USE. The most relevant compounds identified in the extracts were: benzaldehyde (0.9-3.9%), benzoic acid (2.0-11.2%), terpendiol I (0.3-7.4%), coumaran (0.0-2.8%), 2-phenylacetic acid (2.0-26.4%), methyl syringate (3.9-13.1%), vomifoliol (5.0-31.8%), and methyl 1H-indole-3-acetate (1.9-10.2%). Apple honey contained also benzyl alcohol, 2-phenylethanol, (E)-cinnamaldehyde, (E)-cinnamyl alcohol, eugenol, vanillin, and linalool that have been found previously in apple flowers, thus disclosing similarity of both volatile profiles. Copyright © 2013 Verlag Helvetica Chimica Acta AG, Zürich.

  2. Spectroscopic investigation of Ginkgo biloba terpene trilactones and their interaction with amyloid peptide Aβ(25-35)

    Science.gov (United States)

    He, Jiangtao; Petrovic, Ana G.; Dzyuba, Sergei V.; Berova, Nina; Nakanishi, Koji; Polavarapu, Prasad L.

    2008-04-01

    The beneficial effects of Ginkgo biloba extract in the "treatment" of dementia are attributed to its terpene trilactone (TTL) constituents. The interactions between TTLs and amyloid peptide are believed to be responsible in preventing the aggregation of peptide. These interactions have been investigated using infrared vibrational absorption (VA) and circular dichroism (VCD) spectra. Four TTLs, namely ginkgolide A (GA), ginkgolide B (GB), ginkgolide C (GC) and bilobalide (BB) and amyloid Aβ(25-35) peptide, as a model for the full length peptide, are used in this study. GA-monoether and GA-diether have also been synthesized and investigated to help understand the role of individual carbonyl groups in these interactions. The precipitation and solubility issues encountered with the mixture of ginkgolide + Aβ peptide for VA and VCD studies were overcome using binary ethanol-D 2O solvent mixture. The experimental VA and VCD spectra of GA, GB, GC and BB, GA-monoether and GA-diether have been analyzed using the corresponding spectra predicted with density functional theory. The time-dependent experimental VA and VCD spectra of Aβ(25-35) peptide and the corresponding experimental spectra in the presence of TTLs indicated that the effect of the TTLs in modulating the aggregation of Aβ(25-35) peptide is relatively small. Such small effects might indicate the absence of a specific interaction between the TTLs and Aβ(25-35) peptide as a major force leading to the reduced aggregation of amyloid peptides. It is possible that the therapeutic effect of G. biloba extract does not originate from direct interactions between TTLs and the Aβ(25-35) peptide and is more complex.

  3. Molecular cloning and functional characterization of three terpene synthases from unripe fruit of black pepper (Piper nigrum).

    Science.gov (United States)

    Jin, Zhehao; Kwon, Moonhyuk; Lee, Ah-Reum; Ro, Dae-Kyun; Wungsintaweekul, Juraithip; Kim, Soo-Un

    2018-01-15

    To identify terpene synthases (TPS) responsible for the biosynthesis of the sesquiterpenes that contribute to the characteristic flavors of black pepper (Piper nigrum), unripe peppercorn was subjected to the Illumina transcriptome sequencing. The BLAST analysis using amorpha-4,11-diene synthase as a query identified 19 sesquiterpene synthases (sesqui-TPSs), of which three full-length cDNAs (PnTPS1 through 3) were cloned. These sesqui-TPS cDNAs were expressed in E. coli to produce recombinant enzymes for in vitro assays, and also expressed in the engineered yeast strain to assess their catalytic activities in vivo. PnTPS1 produced β-caryophyllene as a main product and humulene as a minor compound, and thus was named caryophyllene synthase (PnCPS). Likewise, PnTPS2 and PnTPS3 were, respectively, named cadinol/cadinene synthase (PnCO/CDS) and germacrene D synthase (PnGDS). PnGDS expression in yeast yielded β-cadinene and α-copaene, the rearrangement products of germacrene D. Their k cat /K m values (20-37.7 s -1  mM -1 ) were comparable to those of other sesqui-TPSs. Among three PnTPSs, the transcript level of PnCPS was the highest, correlating with the predominant β-caryophyllene biosynthesis in the peppercorn. The products and rearranged products of three PnTPSs could account for about a half of the sesquiterpenes in number found in unripe peppercorn. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Zograscopic Viewing

    Directory of Open Access Journals (Sweden)

    Jan Koenderink

    2013-05-01

    Full Text Available The “zograscope” is a “visual aid” (commonly known as “optical machine” in the 18th century invented in the mid-18th century, and in general use until the early 20th century. It was intended to view single pictures (thus not stereographic pairs with both eyes. The optics approximately eliminates the physiological cues (binocular disparity, vergence, accommodation, movement parallax, and image blur that might indicate the flatness of the picture surface. The spatial structure of pictorial space is due to the remaining pictorial cues. As a consequence, many (or perhaps most observers are aware of a heightened “plasticity” of the pictorial content for zograscopic as compared with natural viewing. We discuss the optics of the zograscope in some detail. Such an analysis is not available in the literature, whereas common “explanations” of the apparatus are evidently nonsensical. We constructed a zograscope, using modern parts, and present psychophysical data on its performance.

  5. Mathematical Description and Mechanistic Reasoning: A Pathway toward STEM Integration

    Science.gov (United States)

    Weinberg, Paul J.

    2017-01-01

    Because reasoning about mechanism is critical to disciplined inquiry in science, technology, engineering, and mathematics (STEM) domains, this study focuses on ways to support the development of this form of reasoning. This study attends to how mechanistic reasoning is constituted through mathematical description. This study draws upon Smith's…

  6. Kinetic, mechanistic and spectral investigation of ruthenium (III ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 117; Issue 1. Kinetic, mechanistic and spectral investigation of ruthenium (III)-catalysed oxidation of atenolol by alkaline permanganate (stopped-flow technique). Rahamatalla M Mulla Gurubasavaraj C Hiremath Sharanappa T Nandibewoor. Full Papers Volume 117 ...

  7. Advanced reach tool (ART) : Development of the mechanistic model

    NARCIS (Netherlands)

    Fransman, W.; Tongeren, M. van; Cherrie, J.W.; Tischer, M.; Schneider, T.; Schinkel, J.; Kromhout, H.; Warren, N.; Goede, H.; Tielemans, E.

    2011-01-01

    This paper describes the development of the mechanistic model within a collaborative project, referred to as the Advanced REACH Tool (ART) project, to develop a tool to model inhalation exposure for workers sharing similar operational conditions across different industries and locations in Europe.

  8. Generative Mechanistic Explanation Building in Undergraduate Molecular and Cellular Biology

    Science.gov (United States)

    Southard, Katelyn M.; Espindola, Melissa R.; Zaepfel, Samantha D.; Bolger, Molly S.

    2017-01-01

    When conducting scientific research, experts in molecular and cellular biology (MCB) use specific reasoning strategies to construct mechanistic explanations for the underlying causal features of molecular phenomena. We explored how undergraduate students applied this scientific practice in MCB. Drawing from studies of explanation building among…

  9. Does Mechanistic Thinking Improve Student Success in Organic Chemistry?

    Science.gov (United States)

    Grove, Nathaniel P.; Cooper, Melanie M.; Cox, Elizabeth L.

    2012-01-01

    The use of the curved-arrow notation to depict electron flow during mechanistic processes is one of the most important representational conventions in the organic chemistry curriculum. Our previous research documented a disturbing trend: when asked to predict the products of a series of reactions, many students do not spontaneously engage in…

  10. Mechanistic model for dispersion coefficients in bubble column

    CSIR Research Space (South Africa)

    Skosana, PJ

    2015-05-01

    Full Text Available A mechanistic model describing the mass and momentum exchange in bubble columns is proposed that is based on the observations that the gas distribution in a bubble column is not uniform across the column and that as a consequence large liquid...

  11. Mechanistically Consistent Reduced Models of Synthetic Gene Networks

    Science.gov (United States)

    Mier-y-Terán-Romero, Luis; Silber, Mary; Hatzimanikatis, Vassily

    2013-01-01

    Designing genetic networks with desired functionalities requires an accurate mathematical framework that accounts for the essential mechanistic details of the system. Here, we formulate a time-delay model of protein translation and mRNA degradation by systematically reducing a detailed mechanistic model that explicitly accounts for the ribosomal dynamics and the cleaving of mRNA by endonucleases. We exploit various technical and conceptual advantages that our time-delay model offers over the mechanistic model to probe the behavior of a self-repressing gene over wide regions of parameter space. We show that a heuristic time-delay model of protein synthesis of a commonly used form yields a notably different prediction for the parameter region where sustained oscillations occur. This suggests that such heuristics can lead to erroneous results. The functional forms that arise from our systematic reduction can be used for every system that involves transcription and translation and they could replace the commonly used heuristic time-delay models for these processes. The results from our analysis have important implications for the design of synthetic gene networks and stress that such design must be guided by a combination of heuristic models and mechanistic models that include all relevant details of the process. PMID:23663853

  12. The mechanistic bases of the power-time relationship

    DEFF Research Database (Denmark)

    Vanhatalo, Anni; Black, Matthew I; DiMenna, Fred J

    2016-01-01

    .025) and inversely correlated with muscle type IIx fibre proportion (r = -0.76, P = 0.01). There was no relationship between W' (19.4 ± 6.3 kJ) and muscle fibre type. These data indicate a mechanistic link between the bioenergetic characteristics of different muscle fibre types and the power-duration relationship...

  13. A mechanistic model on methane oxidation in the rice rhizosphere

    NARCIS (Netherlands)

    Bodegom, van P.M.; Leffelaar, P.A.; Goudriaan, J.

    2001-01-01

    A mechanistic model is presented on the processes leading to methane oxidation in rice rhizosphere. The model is driven by oxygen release from a rice root into anaerobic rice soil. Oxygen is consumed by heterotrophic and methanotrophic respiration, described by double Monod kinetics, and by iron

  14. Descriptive and mechanistic models of crop–weed competition

    NARCIS (Netherlands)

    Bastiaans, L.; Storkey, J.

    2017-01-01

    Crop-weed competitive relations are an important element of agroecosystems. Quantifying and understanding them helps to design appropriate weed management at operational, tactical and strategic level. This chapter presents and discusses simple descriptive and more mechanistic models for crop-weed

  15. Mechanistic Insight of Probiotics Derived Anticancer Pharmaceuticals: A Road Forward for Cancer Therapeutics.

    Science.gov (United States)

    Kumar, Raman; Dhanda, Suman

    2017-04-01

    Probiotics are living organisms that confer health benefits when administered in adequate amounts. Probiotics are continuously being explored for their different health beneficiary activities. Anticancer activity is one of the most important benefits both from a preventive and therapeutic point of view. Though not many studies have been conducted to date in this area, a number suggest using laboratory animal models and different cell lines that there may be a mechanistic basis for the anticancer effects of probiotics and require more scientific justification and clinical trials. Most studies of probiotics are conducted for colon cancer associated with inflammatory bowel disease. Studies are also being extended to other types of cancer in different cell lines. This review summarizes studied probiotics considered for treatment of colon cancer and some other cancers (in cancer cell lines) and also proposed mechanism how probiotics are inhibiting cancer growth along with some challenges and future perspectives.

  16. Mechanistic causality and counterfactual-manipulative causality: recent insights from philosophy of science.

    Science.gov (United States)

    Campaner, Raffaella

    2011-12-01

    Current epidemiological and statistical theory about research methods and how to elicit causation from epidemiological studies is strongly influenced by counterfactual-manipulative thinking. However, thinking about how disease states develop is rooted in mechanistic 'webs of causes'. After a tremendous growth of research in molecular biology, biochemistry and genetics, attention has increasingly been paid to environmental and socioeconomic factors as determinants of diseases. This led to conceiving of most pathologies as caused by multilevel mechanical systems. The nature of 'mechanisms' has been the subject of extensive philosophical reflection over the past couple of decades. The present paper will first present some of today's philosophical insights in what are called biologic or other 'mechanisms' and thereafter show how these concepts can be linked to counterfactual-manipulative views.

  17. Unification and mechanistic detail as drivers of model construction: models of networks in economics and sociology.

    Science.gov (United States)

    Kuorikoski, Jaakko; Marchionni, Caterina

    2014-12-01

    We examine the diversity of strategies of modelling networks in (micro) economics and (analytical) sociology. Field-specific conceptions of what explaining (with) networks amounts to or systematic preference for certain kinds of explanatory factors are not sufficient to account for differences in modelling methodologies. We argue that network models in both sociology and economics are abstract models of network mechanisms and that differences in their modelling strategies derive to a large extent from field-specific conceptions of the way in which a good model should be a general one. Whereas the economics models aim at unification, the sociological models aim at a set of mechanism schemas that are extrapolatable to the extent that the underlying psychological mechanisms are general. These conceptions of generality induce specific biases in mechanistic explanation and are related to different views of when knowledge from different fields should be seen as relevant.

  18. Blood-brain barrier disruption: mechanistic links between Western diet consumption and dementia

    Directory of Open Access Journals (Sweden)

    Ted Menghsiung Hsu

    2014-05-01

    Full Text Available Both obesity and Alzheimer’s disease are major health burdens in Western societies. While commonly viewed as having separate etiologies, this review highlights data suggesting that intake of Western diets, diets high in saturated fatty acids and simple carbohydrates, may pose a common environmental risk factor contributing to the development of both of these adverse pathologies. We discuss the effects of Western Diet intake on learning and memory processes that are dependent on the hippocampus, as well as the importance of this brain region in both obesity development and the onset of Alzheimer’s and other dementias. A putative mechanism is discussed that mechanistically links Western diet consumption, blood brain barrier degradation, and subsequent hippocampal damage and dementia pathology.

  19. Can contact allergy to p-phenylenediamine explain the high rates of terpene hydroperoxide allergy? - An epidemiological study based on consecutive patch test results

    DEFF Research Database (Denmark)

    Bennike, Niels Højsager; Lepoittevin, Jean-Pierre; Johansen, Jeanne D

    2017-01-01

    BACKGROUND: Contact allergy to linalool hydroperoxides (Lin-OOHs) and limonene hydroperoxides (Lim-OOHs) is common. Similarly to what occurs with the terpene hydroperoxides, reactive intermediates formed from p-phenylenediamine (PPD) can cause oxidative modifications of tryptophan residues...... increased risk (OR 2.11, 95%CI:0.92-4.80) of a positive patch test reaction to Lin-OOHs. CONCLUSIONS: PPD sensitization cannot explain the high rates of sensitization to Lin-OOHs and/or Lim-OOHs. Contact allergy to oxidized linalool is more strongly associated with fragrance allergy than with PPD allergy....

  20. Differential response of terpenes and anthraquinones derivatives in Rumex dentatus and Lavandula officinalis to harsh winters across north-western Himalaya.

    Science.gov (United States)

    Jan, Sumira; Kamili, Azra N; Parray, Javid A; Bedi, Yashbir S

    2016-01-01

    Herbs adapted to diverse climates exhibit distinct variability to fluctuating temperatures and demonstrate various metabolic and physiological adaptations to harsh environments. In this research, Rumex dentatus L. and Lavandula officinalis L. were collected before snowfall in September-November to evaluate variability in major phytoconstituents to diverse seasonal regime. LC-MS was used for simultaneous determination of eight anthraquinone derivatives in R. dentatus, i.e. emodin, physcion, chrysophanol, physcion glucoside, endocrocin, emodin glucoside, chrysophanol glucoside and chromone derivatives and monoterpenes in L. officinalis i.e. (Z)-β-ocimene, (E)-β-ocimene, terpene alcohol, terpin-4-ol, acetate ester-linalyl acetate and bicyclic sesquiterpene (E)-caryophyllene. The correlation analysis confirmed significant variation in anthraquinone glucoside and terpene content within Rumex and Lavender, respectively, and altitude was established as the determinant factor in secondary metabolism of both herbs. The study concludes the propagation of herbs in bioclimatic belts which favour accumulation of major constituents and validate their greater pharmacological activity.

  1. Functional identification of valerena-1,10-diene synthase, a terpene synthase catalyzing a unique chemical cascade in the biosynthesis of biologically active sesquiterpenes in Valeriana officinalis.

    Science.gov (United States)

    Yeo, Yun-Soo; Nybo, S Eric; Chittiboyina, Amar G; Weerasooriya, Aruna D; Wang, Yan-Hong; Góngora-Castillo, Elsa; Vaillancourt, Brieanne; Buell, C Robin; DellaPenna, Dean; Celiz, Mary Dawn; Jones, A Daniel; Wurtele, Eve Syrkin; Ransom, Nick; Dudareva, Natalia; Shaaban, Khaled A; Tibrewal, Nidhi; Chandra, Suman; Smillie, Troy; Khan, Ikhlas A; Coates, Robert M; Watt, David S; Chappell, Joe

    2013-02-01

    Valerian is an herbal preparation from the roots of Valeriana officinalis used as an anxiolytic and sedative and in the treatment of insomnia. The biological activities of valerian are attributed to valerenic acid and its putative biosynthetic precursor valerenadiene, sesquiterpenes, found in V. officinalis roots. These sesquiterpenes retain an isobutenyl side chain whose origin has been long recognized as enigmatic because a chemical rationalization for their biosynthesis has not been obvious. Using recently developed metabolomic and transcriptomic resources, we identified seven V. officinalis terpene synthase genes (VoTPSs), two that were functionally characterized as monoterpene synthases and three that preferred farnesyl diphosphate, the substrate for sesquiterpene synthases. The reaction products for two of the sesquiterpene synthases exhibiting root-specific expression were characterized by a combination of GC-MS and NMR in comparison to the terpenes accumulating in planta. VoTPS7 encodes for a synthase that biosynthesizes predominately germacrene C, whereas VoTPS1 catalyzes the conversion of farnesyl diphosphate to valerena-1,10-diene. Using a yeast expression system, specific labeled [(13)C]acetate, and NMR, we investigated the catalytic mechanism for VoTPS1 and provide evidence for the involvement of a caryophyllenyl carbocation, a cyclobutyl intermediate, in the biosynthesis of valerena-1,10-diene. We suggest a similar mechanism for the biosynthesis of several other biologically related isobutenyl-containing sesquiterpenes.

  2. Identification and characterization of (E)-β-caryophyllene synthase and α/β-pinene synthase potentially involved in constitutive and herbivore-induced terpene formation in cotton.

    Science.gov (United States)

    Huang, Xinzheng; Xiao, Yutao; Köllner, Tobias G; Zhang, Wanna; Wu, Junxiang; Wu, Juan; Guo, Yuyuan; Zhang, Yongjun

    2013-12-01

    Cotton (Gossypium hirsutum L.) plants damaged by insects emit a blend of volatiles, including monoterpenes and sesquiterpenes, which can directly repel herbivores and/or indirectly protect the plant by attracting natural enemies of the herbivores. To understand the molecular basis of terpene biosynthesis and regulation in cotton, two terpene synthase genes, GhTPS1 and GhTPS2, were heterologously expressed and characterized. Recombinant GhTPS1 accepted farnesyl pyrophosphate as substrate and produced (E)-β-caryophyllene and α-humulene. GhTPS2 was characterized as a monoterpene synthase which formed α-pinene and β-pinene using geranyl pyrophosphate as substrate. Quantitative real-time PCR analysis revealed that GhTPS1 and GhTPS2 gene expression was elevated after methyl jasmonate (MeJA) treatment in cotton leaves. Moreover, feeding of the green plant bug Apolygus lucorum, a major cotton pest in northern China, resulted in increased GhTPS2 expression in young leaves, suggesting that GhTPS2 might be involved in plant defense in cotton. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  3. Metabolic engineering of terpene biosynthesis in plants using a trichome-specific transcription factor MsYABBY5 from spearmint (Mentha spicata).

    Science.gov (United States)

    Wang, Qian; Reddy, Vaishnavi Amarr; Panicker, Deepa; Mao, Hui-Zhu; Kumar, Nadimuthu; Rajan, Chakravarthy; Venkatesh, Prasanna Nori; Chua, Nam-Hai; Sarojam, Rajani

    2016-07-01

    In many aromatic plants including spearmint (Mentha spicata), the sites of secondary metabolite production are tiny specialized structures called peltate glandular trichomes (PGT). Having high commercial values, these secondary metabolites are exploited largely as flavours, fragrances and pharmaceuticals. But, knowledge about transcription factors (TFs) that regulate secondary metabolism in PGT remains elusive. Understanding the role of TFs in secondary metabolism pathway will aid in metabolic engineering for increased yield of secondary metabolites and also the development of new production techniques for valuable metabolites. Here, we isolated and functionally characterized a novel MsYABBY5 gene that is preferentially expressed in PGT of spearmint. We generated transgenic plants in which MsYABBY5 was either overexpressed or silenced using RNA interference (RNAi). Analysis of the transgenic lines showed that the reduced expression of MsYABBY5 led to increased levels of terpenes and that overexpression decreased terpene levels. Additionally, ectopic expression of MsYABBY5 in Ocimum basilicum and Nicotiana sylvestris decreased secondary metabolite production in them, suggesting that the encoded transcription factor is probably a repressor of secondary metabolism. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

  4. Functional Identification of Valerena-1,10-diene Synthase, a Terpene Synthase Catalyzing a Unique Chemical Cascade in the Biosynthesis of Biologically Active Sesquiterpenes in Valeriana officinalis*

    Science.gov (United States)

    Yeo, Yun-Soo; Nybo, S. Eric; Chittiboyina, Amar G.; Weerasooriya, Aruna D.; Wang, Yan-Hong; Góngora-Castillo, Elsa; Vaillancourt, Brieanne; Buell, C. Robin; DellaPenna, Dean; Celiz, Mary Dawn; Jones, A. Daniel; Wurtele, Eve Syrkin; Ransom, Nick; Dudareva, Natalia; Shaaban, Khaled A.; Tibrewal, Nidhi; Chandra, Suman; Smillie, Troy; Khan, Ikhlas A.; Coates, Robert M.; Watt, David S.; Chappell, Joe

    2013-01-01

    Valerian is an herbal preparation from the roots of Valeriana officinalis used as an anxiolytic and sedative and in the treatment of insomnia. The biological activities of valerian are attributed to valerenic acid and its putative biosynthetic precursor valerenadiene, sesquiterpenes, found in V. officinalis roots. These sesquiterpenes retain an isobutenyl side chain whose origin has been long recognized as enigmatic because a chemical rationalization for their biosynthesis has not been obvious. Using recently developed metabolomic and transcriptomic resources, we identified seven V. officinalis terpene synthase genes (VoTPSs), two that were functionally characterized as monoterpene synthases and three that preferred farnesyl diphosphate, the substrate for sesquiterpene synthases. The reaction products for two of the sesquiterpene synthases exhibiting root-specific expression were characterized by a combination of GC-MS and NMR in comparison to the terpenes accumulating in planta. VoTPS7 encodes for a synthase that biosynthesizes predominately germacrene C, whereas VoTPS1 catalyzes the conversion of farnesyl diphosphate to valerena-1,10-diene. Using a yeast expression system, specific labeled [13C]acetate, and NMR, we investigated the catalytic mechanism for VoTPS1 and provide evidence for the involvement of a caryophyllenyl carbocation, a cyclobutyl intermediate, in the biosynthesis of valerena-1,10-diene. We suggest a similar mechanism for the biosynthesis of several other biologically related isobutenyl-containing sesquiterpenes. PMID:23243312

  5. Mechanistic Fermentation Models for Process Design, Monitoring, and Control.

    Science.gov (United States)

    Mears, Lisa; Stocks, Stuart M; Albaek, Mads O; Sin, Gürkan; Gernaey, Krist V

    2017-10-01

    Mechanistic models require a significant investment of time and resources, but their application to multiple stages of fermentation process development and operation can make this investment highly valuable. This Opinion article discusses how an established fermentation model may be adapted for application to different stages of fermentation process development: planning, process design, monitoring, and control. Although a longer development time is required for such modeling methods in comparison to purely data-based model techniques, the wide range of applications makes them a highly valuable tool for fermentation research and development. In addition, in a research environment, where collaboration is important, developing mechanistic models provides a platform for knowledge sharing and consolidation of existing process understanding. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. The evolution of honey bee dance communication: a mechanistic perspective.

    Science.gov (United States)

    Barron, Andrew B; Plath, Jenny Aino

    2017-12-01

    Honey bee dance has been intensively studied as a communication system, and yet we still know very little about the neurobiological mechanisms supporting how dances are produced and interpreted. Here, we discuss how new information on the functions of the central complex (CX) of the insect brain might shed some light on possible neural mechanisms of dance behaviour. We summarise the features of dance communication across the species of the genus Apis We then propose that neural mechanisms of orientation and spatial processing found to be supported by the CX may function in dance communication also, and that this mechanistic link could explain some specific features of the dance form. This is purely a hypothesis, but in proposing this hypothesis, and how it might be investigated, we hope to stimulate new mechanistic analyses of dance communication. © 2017. Published by The Company of Biologists Ltd.

  7. Mechanistic Fermentation Models for Process Design, Monitoring, and Control

    DEFF Research Database (Denmark)

    Mears, Lisa; Stocks, Stuart M.; Albæk, Mads Orla

    2017-01-01

    Mechanistic models require a significant investment of time and resources, but their application to multiple stages of fermentation process development and operation can make this investment highly valuable. This Opinion article discusses how an established fermentation model may be adapted...... for application to different stages of fermentation process development: planning, process design, monitoring, and control. Although a longer development time is required for such modeling methods in comparison to purely data-based model techniques, the wide range of applications makes them a highly valuable tool...... for fermentation research and development. In addition, in a research environment, where collaboration is important, developing mechanistic models provides a platform for knowledge sharing and consolidation of existing process understanding....

  8. Mechanistic model and analysis of doxorubicin release from liposomal formulations.

    Science.gov (United States)

    Fugit, Kyle D; Xiang, Tian-Xiang; Choi, Du H; Kangarlou, Sogol; Csuhai, Eva; Bummer, Paul M; Anderson, Bradley D

    2015-11-10

    Reliable and predictive models of drug release kinetics in vitro and in vivo are still lacking for liposomal formulations. Developing robust, predictive release models requires systematic, quantitative characterization of these complex drug delivery systems with respect to the physicochemical properties governing the driving force for release. These models must also incorporate changes in release due to the dissolution media and methods employed to monitor release. This paper demonstrates the successful development and application of a mathematical mechanistic model capable of predicting doxorubicin (DXR) release kinetics from liposomal formulations resembling the FDA-approved nanoformulation DOXIL® using dynamic dialysis. The model accounts for DXR equilibria (e.g. self-association, precipitation, ionization), the change in intravesicular pH due to ammonia release, and dialysis membrane transport of DXR. The model was tested using a Box-Behnken experimental design in which release conditions including extravesicular pH, ammonia concentration in the release medium, and the dilution of the formulation (i.e. suspension concentration) were varied. Mechanistic model predictions agreed with observed DXR release up to 19h. The predictions were similar to a computer fit of the release data using an empirical model often employed for analyzing data generated from this type of experimental design. Unlike the empirical model, the mechanistic model was also able to provide reasonable predictions of release outside the tested design space. These results illustrate the usefulness of mechanistic modeling to predict drug release from liposomal formulations in vitro and its potential for future development of in vitro - in vivo correlations for complex nanoformulations. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Antioxidative activity of caffeic acid: Mechanistic DFT study

    OpenAIRE

    Redžepović, Izudin; Marković, Svetlana; Tošović, Jelena

    2017-01-01

    This paper reports the results of comprehensive mechanistic investigations of the hydrogen atom transfer (HAT), radical adduct formation (RAF), single electron transfer – proton transfer (SET-PT), and sequential proton loss electron transfer (SPLET) mechanisms of caffeic acid (CA). The goals of the work were achieved by simulating the reactions of CA with hydroxyl radical in benzene and water solutions. It was found that SET-PT is not a favourable antioxidative mechanism of CA. On the other h...

  10. Regulation of Terpene Metabolism

    Energy Technology Data Exchange (ETDEWEB)

    Rodney Croteau

    2004-03-14

    OAK-B135 Research over the last four years has progressed fairly closely along the lines initially proposed, with progress-driven expansion of Objectives 1, 2 and 3. Recent advances have developed from three research thrusts: 1. Random sequencing of an enriched peppermint oil gland cDNA library has given access to a large number of potential pathway and regulatory genes for test of function; 2. The availability of new DNA probes and antibodies has permitted investigation of developmental regulation and organization of terpenoid metabolism; and 3. The development of a transformation system for peppermint by colleagues at Purdue University has allowed direct transgenic testing of gene function and added a biotechnological component to the project. The current status of each of the original research objectives is outlined below.

  11. Development of mechanistic sorption model and treatment of uncertainties for Ni sorption on montmorillonite/bentonite

    International Nuclear Information System (INIS)

    Ochs, Michael; Ganter, Charlotte; Tachi, Yukio; Suyama, Tadahiro; Yui, Mikazu

    2011-02-01

    Sorption and diffusion of radionuclides in buffer materials (bentonite) are the key processes in the safe geological disposal of radioactive waste, because migration of radionuclides in this barrier is expected to be diffusion-controlled and retarded by sorption processes. It is therefore necessary to understand the detailed/coupled processes of sorption and diffusion in compacted bentonite and develop mechanistic /predictive models, so that reliable parameters can be set under a variety of geochemical conditions relevant to performance assessment (PA). For this purpose, JAEA has developed the integrated sorption and diffusion (ISD) model/database in montmorillonite/bentonite systems. The main goal of the mechanistic model/database development is to provide a tool for a consistent explanation, prediction, and uncertainty assessment of K d as well as diffusion parameters needed for the quantification of radionuclide transport. The present report focuses on developing the thermodynamic sorption model (TSM) and on the quantification and handling of model uncertainties in applications, based on illustrating by example of Ni sorption on montmorillonite/bentonite. This includes 1) a summary of the present state of the art of thermodynamic sorption modeling, 2) a discussion of the selection of surface species and model design appropriate for the present purpose, 3) possible sources and representations of TSM uncertainties, and 4) details of modeling, testing and uncertainty evaluation for Ni sorption. Two fundamentally different approaches are presented and compared for representing TSM uncertainties: 1) TSM parameter uncertainties calculated by FITEQL optimization routines and some statistical procedure, 2) overall error estimated by direct comparison of modeled and experimental K d values. The overall error in K d is viewed as the best representation of model uncertainty in ISD model/database development. (author)

  12. Modeling with the logistic regression of the growth/no growth interface of Saccharomyces cerevisiae in relation to 2 antimicrobial terpenes (citral and linalool), pH, and a(w).

    Science.gov (United States)

    Tabanelli, Giulia; Montanari, Chiara; Patrignani, Francesca; Siroli, Lorenzo; Lanciotti, Rosalba; Gardini, Fausto

    2014-03-01

    The antimicrobial effects of 2 terpenes (citral and linalool) on a Saccharomyces cerevisiae strain isolated from spoiled soft drink have been evaluated, alone or in combination, in relation to pH and aw using in vitro assays. The obtained data were fitted with the logit model to find the growth/no growth boundary regions of the 2 terpenes, focusing the attention on the type of interaction exerted by citral and linalool. In particular, the results showed an increase of citral antimicrobial effect in growth media characterized by low aw value, as well as a higher linalool antimicrobial effect in media at low pH. Moreover, the interactive effects of the 2 terpenes were exploited. The results obtained with the model were validated in an independent experiment. The knowledge of the interactions of essential oil molecules with enhanced antimicrobial activity, in relation to some of the most important chemicophysical variables, can have important industrial applications, since these substances are able to assure the desired antimicrobial effect without negatively modifying the product flavor profile. The effects of the main chemicophysical parameters (such as aw and pH) on the antimicrobial activity of bioactive terpenes are necessary for the definition of an industrially applicable preservation strategy based on the use of essential oils as natural antimicrobials aimed to prolong shelf life of food products. © 2014 Institute of Food Technologists®

  13. A maize landrace that emits defense volatiles in response to herbivore eggs possesses a strongly inducible terpene synthase gene.

    Science.gov (United States)

    Tamiru, Amanuel; Bruce, Toby J A; Richter, Annett; Woodcock, Christine M; Midega, Charles A O; Degenhardt, Jörg; Kelemu, Segenet; Pickett, John A; Khan, Zeyaur R

    2017-04-01

    Maize ( Zea mays ) emits volatile terpenes in response to insect feeding and egg deposition to defend itself against harmful pests. However, maize cultivars differ strongly in their ability to produce the defense signal. To further understand the agroecological role and underlying genetic mechanisms for variation in terpene emission among maize cultivars, we studied the production of an important signaling component ( E )-caryophyllene in a South American maize landrace Braz1006 possessing stemborer Chilo partellus egg inducible defense trait, in comparison with the European maize line Delprim and North American inbred line B73. The ( E) - caryophyllene production level and transcript abundance of TPS23, terpene synthase responsible for ( E) - caryophyllene formation, were compared between Braz1006, Delprim, and B73 after mimicked herbivory. Braz1006-TPS23 was heterologously expressed in E. coli , and amino acid sequences were determined. Furthermore, electrophysiological and behavioral responses of a key parasitic wasp Cotesia sesamiae to C .  partellus egg-induced Braz1006 volatiles were determined using coupled gas chromatography electroantennography and olfactometer bioassay studies. After elicitor treatment, Braz1006 released eightfold higher ( E) -caryophyllene than Delprim, whereas no ( E) -caryophyllene was detected in B73. The superior (E)- caryophyllene production by Braz1006 was positively correlated with high transcript levels of TPS23 in the landrace compared to Delprim. TPS23 alleles from Braz1006 showed dissimilarities at different sequence positions with Delprim and B73 and encodes an active enzyme. Cotesia sesamiae was attracted to egg-induced volatiles from Braz1006 and synthetic (E)- caryophyllene. The variation in ( E) -caryophyllene emission between Braz1006 and Delprim is positively correlated with induced levels of TPS23 transcripts. The enhanced TPS23 activity and corresponding ( E) -caryophyllene production by the maize landrace could be

  14. Structure of active IspH enzyme from escherichia coli provides mechanistic insights into substrate reduction

    KAUST Repository

    Gräwert, Tobias

    2009-07-20

    The terminal step of the non-mevalonate pathway of terpene biosynthesis is catalyzed by IspH (see scheme). In the crystal structure of IspH from E. coli, a bound inorganic diphosphate ligand occupies the position of the diphosphate residue of the substrate. Together with mutation studies and theoretical calculations, these data support a mechanism which is analogous to the Birch reduction of allylic alcohols. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA.

  15. Molecular responses to xenoestrogens: mechanistic insights from toxicogenomics.

    Science.gov (United States)

    Moggs, Jonathan G

    2005-10-01

    The xenoestrogen group of endocrine disruptors has the potential to cause reproductive and developmental effects through stimulation or disruption of sex steroid nuclear receptor signalling pathways. A more detailed understanding of the ways in which xenoestrogens interact with biological systems at the molecular level will provide a mechanistic basis for improved safety assessment. The recent sequencing of mammalian genomes has driven the development of toxicogenomic technologies, including microarray based gene expression profiling, which allow the expression levels of thousands of genes to be measured simultaneously. Since the cellular responses to xenoestrogens are predominantly mediated by estrogen receptors, which function as ligand-activated transcription factors to regulate gene expression, the application of toxicogenomics has great potential for providing insights into the molecular mechanisms of xenoestrogen action. A major challenge in applying toxicogenomics to the field of endocrine disruption is the need to define how xenoestrogen-induced changes in gene expression relate to conventional physiological and toxicological endpoints. Gene Ontology Mapping, Pathway Mapping and Phenotypic Anchoring of xenoestrogen-induced gene expression changes to cellular pathways and processes represent key steps in defining these relationships. Mechanistic insights into how xenoestrogens target specific genes and into the functional significance of xenoestrogen-induced alterations in gene expression can be further enhanced by combining transcript profiling with transgenic animal models or cell-based systems in which the estrogen receptor signalling pathways have been modified experimentally. This review illustrates how these toxicogenomic approaches are providing an unprecedented amount of mechanistic information on the molecular responses to xenoestrogens and how they are likely to impact on hazard and risk assessment.

  16. Molecular responses to xenoestrogens: Mechanistic insights from toxicogenomics

    International Nuclear Information System (INIS)

    Moggs, Jonathan G.

    2005-01-01

    The xenoestrogen group of endocrine disruptors has the potential to cause reproductive and developmental effects through stimulation or disruption of sex steroid nuclear receptor signalling pathways. A more detailed understanding of the ways in which xenoestrogens interact with biological systems at the molecular level will provide a mechanistic basis for improved safety assessment. The recent sequencing of mammalian genomes has driven the development of toxicogenomic technologies, including microarray based gene expression profiling, which allow the expression levels of thousands of genes to be measured simultaneously. Since the cellular responses to xenoestrogens are predominantly mediated by estrogen receptors, which function as ligand-activated transcription factors to regulate gene expression, the application of toxicogenomics has great potential for providing insights into the molecular mechanisms of xenoestrogen action. A major challenge in applying toxicogenomics to the field of endocrine disruption is the need to define how xenoestrogen-induced changes in gene expression relate to conventional physiological and toxicological endpoints. Gene Ontology Mapping, Pathway Mapping and Phenotypic Anchoring of xenoestrogen-induced gene expression changes to cellular pathways and processes represent key steps in defining these relationships. Mechanistic insights into how xenoestrogens target specific genes and into the functional significance of xenoestrogen-induced alterations in gene expression can be further enhanced by combining transcript profiling with transgenic animal models or cell-based systems in which the estrogen receptor signalling pathways have been modified experimentally. This review illustrates how these toxicogenomic approaches are providing an unprecedented amount of mechanistic information on the molecular responses to xenoestrogens and how they are likely to impact on hazard and risk assessment

  17. Adverse outcome pathways: Application to enhance mechanistic understanding of neurotoxicity.

    Science.gov (United States)

    Bal-Price, Anna; Meek, M E Bette

    2017-11-01

    Recent developments have prompted the transition of empirically based testing of late stage toxicity in animals for a range of different endpoints including neurotoxicity to more efficient and predictive mechanistically based approaches with greater emphasis on measurable key events early in the progression of disease. The adverse outcome pathway (AOP) has been proposed as a simplified organizational construct to contribute to this transition by linking molecular initiating events and earlier (more predictive) key events at lower levels of biological organization to disease outcomes. As such, AOPs are anticipated to facilitate the compilation of information to increase mechanistic understanding of pathophysiological pathways that are responsible for human disease. In this review, the sequence of key events resulting in adverse outcome (AO) defined as parkinsonian motor impairment and learning and memory deficit in children, triggered by exposure to environmental chemicals has been briefly described using the AOP framework. These AOPs follow convention adopted in an Organization for Economic Cooperation and Development (OECD) AOP development program, publically available, to permit tailored application of AOPs for a range of different purposes. Due to the complexity of disease pathways, including neurodegenerative disorders, a specific symptom of the disease (e.g. parkinsonian motor deficit) is considered as the AO in a developed AOP. Though the description is necessarily limited by the extent of current knowledge, additional characterization of involved pathways through description of related AOPs interlinked into networks for the same disease has potential to contribute to more holistic and mechanistic understanding of the pathophysiological pathways involved, possibly leading to the mechanism-based reclassification of diseases, thus facilitating more personalized treatment. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  18. Development of Improved Mechanistic Deterioration Models for Flexible Pavements

    DEFF Research Database (Denmark)

    Ullidtz, Per; Ertman, Hans Larsen

    1998-01-01

    The paper describes a pilot study in Denmark with the main objective of developing improved mechanistic deterioration models for flexible pavements based on an accelerated full scale test on an instrumented pavement in the Danish Road Tessting Machine. The study was the first in "International...... Pavement Subgrade Performance Study" sponsored by the Federal Highway Administration (FHWA), USA. The paper describes in detail the data analysis and the resulting models for rutting, roughness, and a model for the plastic strain in the subgrade.The reader will get an understanding of the work needed...

  19. The mechanistic link between health and gut microbiota diversity.

    Science.gov (United States)

    Larsen, Olaf F A; Claassen, Eric

    2018-02-01

    Although numerous reports link a decreased diversity of the gut microbiota to a declined health status, to date no mechanistic motivation for this exists. Here, we show by applying first principles basic graph theory on small networks that higher diversity within such a network indeed leads to more efficient systems and redundancy. Our results quantitatively support earlier hypothetical considerations on gut microbiota richness with respect to these parameters. Our simulations show that higher species diversity leads to higher resilience within small microbiological ecosystems, like being present in the gut microbiota. This notion should provide an ingredient when developing new interventional strategies within the domain of microbiota management.

  20. Mechanistic study of aerosol dry deposition on vegetated canopies

    International Nuclear Information System (INIS)

    Petroff, A.

    2005-04-01

    The dry deposition of aerosols onto vegetated canopies is modelled through a mechanistic approach. The interaction between aerosols and vegetation is first formulated by using a set of parameters, which are defined at the local scale of one surface. The overall deposition is then deduced at the canopy scale through an up-scaling procedure based on the statistic distribution parameters. This model takes into account the canopy structural and morphological properties, and the main characteristics of the turbulent flow. Deposition mechanisms considered are Brownian diffusion, interception, initial and turbulent impaction, initially with coniferous branches and then with entire canopies of different roughness, such as grass, crop field and forest. (author)

  1. Alternating copolymerization of propylene oxide with biorenewable terpene-based cyclic anhydrides: a sustainable route to aliphatic polyesters with high glass transition temperatures.

    Science.gov (United States)

    Van Zee, Nathan J; Coates, Geoffrey W

    2015-02-23

    The alternating copolymerization of propylene oxide with terpene-based cyclic anhydrides catalyzed by chromium, cobalt, and aluminum salen complexes is reported. The use of the Diels-Alder adduct of α-terpinene and maleic anhydride as the cyclic anhydride comonomer results in amorphous polyesters that exhibit glass transition temperatures (Tg ) of up to 109 °C. The polymerization conditions and choice of catalyst have a dramatic impact on the molecular weight distribution, the relative stereochemistry of the diester units along the polymer chain, and ultimately the Tg of the resulting polymer. The aluminum salen complex exhibits exceptional selectivity for copolymerization without transesterification or epimerization side reactions. The resulting polyesters are highly alternating and have high molecular weights and narrow polydispersities. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Responses of Nigella sativa L. to Zinc Excess: Focus on Germination, Growth, Yield and Yield Components, Lipid and Terpene Metabolism, and Total Phenolics and Antioxidant Activities.

    Science.gov (United States)

    Marichali, Ahmed; Dallali, Sana; Ouerghemmi, Saloua; Sebei, Houcine; Casabianca, Hervé; Hosni, Karim

    2016-03-02

    A comprehensive analysis of the responses of Nigella sativa L. to elevated zinc concentrations was assessed in pot experiments. Zn excess supply did not affect the germination but drastically reduced radicle elongation. A concentration-dependent reduction in all growth parameters, yield, and yield components was observed. With the increasing Zn concentrations, total lipid contents decreased and changes in fatty composition toward the production of saturated ones were underscored. Despite the reduction in the seeds essential oil yield, a redirection of the terpene metabolism toward the synthesis of oxygenated compounds has been evidenced. A significant increase in the total phenols and flavonoids contents concomitant with improved antioxidant activities has also been found. Collectively, these results highlight the possible use of N. sativa L. in phytoremediation applications, on the one hand, and that Zn excess could represent an excellent alternative to improve the nutritional attributes of this important species, on the other hand.

  3. Seasonal Terpene Variation in Needles of Pinus radiata (Pinales: Pinaceae) Trees Attacked by Tomicus piniperda (Coleoptera: Scolytinae) and the Effect of Limonene on Beetle Aggregation.

    Science.gov (United States)

    Romón, Pedro; Aparicio, Domitila; Palacios, Francisco; Iturrondobeitia, Juan Carlos; Hance, Thierry; Goldarazena, Arturo

    2017-09-01

    Concentrations of four monoterpenes were determined in needles of Pinus radiata (D.Don) (Pinales: Pinaceae) trees that were attacked or nonattacked by Tomicus piniperda (L.) (Coleoptera: Scolytinae). Compounds were identified and quantified by gas chromatography-mass spectrometry. The mean ambient temperature was obtained using climate-recording data loggers. The effect of limonene on field aggregation was also evaluated at three limonene release rates using Lindgren attractant-baited traps and trap logs. Attacked trees produced less α-pinene in March, July, and November than nonattacked trees, less β-pinene in July and November, and less limonene from May to November. Limonene reduced the attraction of T. piniperda to attractant-baited traps and trap logs. Results were linked to better responses to high temperatures, with respect to terpene contents, by the nonattacked trees after the spring attack. © The Author 2017. Published by Oxford University Press on behalf of Entomological Society of America.

  4. Changes in volatile terpene and diterpene resin acid composition of resistant and susceptible white spruce leaders exposed to simulated white pine weevil damage.

    Science.gov (United States)

    Tomlin, E S; Antonejevic, E; Alfaro, R I; Borden, J H

    2000-10-01

    Induced (traumatic) resin in white spruce (Picea glauca (Moench) Voss) leaders resistant or susceptible to the white pine weevil (Pissodes strobi Peck) was analyzed for volatile terpenes and diterpene resin acids after simulated white pine weevil damage. Leaders from 331 trees were wounded just below the apical bud with a 1-mm diameter drill, coinciding with the natural time of weevil oviposition in the spring. Leaders were removed in the fall, and the bark and xylem from the upper and lower regions of the leader extracted and analyzed by gas chromatography. Unwounded trees had low amounts of resin in xylem compared with bark. In response to wounding, volatile terpenes and diterpene resin acids increased in the upper xylem (area of wounding), with resistant trees showing a greater increase than susceptible trees. Wounding caused monoterpenes in particular to decrease in the lower region of the leader (away from the drilled area) in greater amounts in susceptible trees than in resistant trees. In response to wounding, the proportion of monoterpene to resin acid increased in the upper and lower xylem of resistant trees, and slightly increased in the upper xylem of susceptible trees. Monoterpene-enriched resin is more fluid than constitutive resin, and probably flows more readily into oviposition cavities and larval mines, where it may kill immature weevils. Loss of resin components in the lower xylem suggested catabolism and transport of these materials to the site of wounding; however, energetic and regulatory data are necessary to confirm this hypothesis. This study provides a basis for measuring the ability of a tree to undergo traumatic resinosis that could be used to screen for resistance to white pine weevil.

  5. Chemical-structural changes during the thermal treatment of hydrogen-rich vitrinites caused by the presence of terpene-type resin

    Energy Technology Data Exchange (ETDEWEB)

    Iglesias, M.J. [Area de Quimica Organica, Universidad de Almeria, Carretera de Sacramento, 04120 Almeria (Spain); Cuesta, M.J.; Suarez-Ruiz, I. [Instituto Nacional del Carbon (CSIC), Ap. Co. 73, 33080 Oviedo (Spain); Laggoun-Defarge, F. [UMR 6531/FR 09 CNRS-Universite d' Orleans, 45067 Orleans, Cedex 2 (France)

    2006-10-15

    The vitrain from Teruel (North-Eastern Spain) is a good example of a vitrinite whose perhydrous character and anomalous properties are caused by the presence of terpene-type resin. The sample used in this work was isothermally pyrolysed in an open-medium system at temperatures ranging from 250 to 500{sup o}C. A mass balance, a petrographic and geochemical characterisation of the pyrolysates and compositional and structural analyses (GC and NMR) of the generated oils were performed. The results confirm the association of huminite-resinous substances through covalent bonds and also point to the possible incorporation of aliphatic material via covalent oxygen bonds. The side-chains that serve as linkers between the phenolic subunits derived from the lignin contain more labile thermal bonds than those present in other vitrinites not affected by resin saturation. Consequently, this type of vitrinite undergoes a more intense degradation at lower temperatures than non-perhydrous and other hydrogen-rich vitrinites. The vitrinite network itself due to the incorporation of resin-like substances (cycloparaffinic in nature) may serve as a hydrogen donor, enhancing the hydrogenation processes during pyrolysis with respect to the polymerisation and recombination reactions. The higher ability of hydrogen to stabilise the free radicals formed during pyrolysis explains the higher conversion to liquids at lower temperatures than in the case of non-perhydrous vitrinites. At the same time, this ability limits the growth of the aromatic structures. The evolution of the vitrinite modified by the presence of terpene-type resin is, thus, retarded with respect to non-perhydrous vitrinites, although in both cases the trend followed is very close. In contrast the trend of this type of vitrinite differs considerably from that of perhydrous vitrinites which are affected by hydrocarbon impregnation. Only for the most severe treatments (450/500{sup o}C) was some degree of structural uniformity

  6. Improving the International Agency for Research on Cancer's consideration of mechanistic evidence.

    Science.gov (United States)

    Goodman, Julie; Lynch, Heather

    2017-03-15

    The International Agency for Research on Cancer (IARC) recently developed a framework for evaluating mechanistic evidence that includes a list of 10 key characteristics of carcinogens. This framework is useful for identifying and organizing large bodies of literature on carcinogenic mechanisms, but it lacks sufficient guidance for conducting evaluations that fully integrate mechanistic evidence into hazard assessments. We summarize the framework, and suggest approaches to strengthen the evaluation of mechanistic evidence using this framework. While the framework is useful for organizing mechanistic evidence, its lack of guidance for implementation limits its utility for understanding human carcinogenic potential. Specifically, it does not include explicit guidance for evaluating the biological significance of mechanistic endpoints, inter- and intra-individual variability, or study quality and relevance. It also does not explicitly address how mechanistic evidence should be integrated with other realms of evidence. Because mechanistic evidence is critical to understanding human cancer hazards, we recommend that IARC develop transparent and systematic guidelines for the use of this framework so that mechanistic evidence will be evaluated and integrated in a robust manner, and concurrently with other realms of evidence, to reach a final human cancer hazard conclusion. IARC does not currently provide a standardized approach to evaluating mechanistic evidence. Incorporating the recommendations discussed here will make IARC analyses of mechanistic evidence more transparent, and lead to assessments of cancer hazards that reflect the weight of the scientific evidence and allow for scientifically defensible decision-making. Copyright © 2017 Gradient. Published by Elsevier Inc. All rights reserved.

  7. Comparison of mechanistic transport cycle models of ABC exporters.

    Science.gov (United States)

    Szöllősi, Dániel; Rose-Sperling, Dania; Hellmich, Ute A; Stockner, Thomas

    2018-04-01

    ABC (ATP binding cassette) transporters, ubiquitous in all kingdoms of life, carry out essential substrate transport reactions across cell membranes. Their transmembrane domains bind and translocate substrates and are connected to a pair of nucleotide binding domains, which bind and hydrolyze ATP to energize import or export of substrates. Over four decades of investigations into ABC transporters have revealed numerous details from atomic-level structural insights to their functional and physiological roles. Despite all these advances, a comprehensive understanding of the mechanistic principles of ABC transporter function remains elusive. The human multidrug resistance transporter ABCB1, also referred to as P-glycoprotein (P-gp), is one of the most intensively studied ABC exporters. Using ABCB1 as the reference point, we aim to compare the dominating mechanistic models of substrate transport and ATP hydrolysis for ABC exporters and to highlight the experimental and computational evidence in their support. In particular, we point out in silico studies that enhance and complement available biochemical data. "This article is part of a Special Issue entitled: Beyond the Structure-Function Horizon of Membrane Proteins edited by Ute Hellmich, Rupak Doshi and Benjamin McIlwain." Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  8. Trichloroethylene: Mechanistic, epidemiologic and other supporting evidence of carcinogenic hazard.

    Science.gov (United States)

    Rusyn, Ivan; Chiu, Weihsueh A; Lash, Lawrence H; Kromhout, Hans; Hansen, Johnni; Guyton, Kathryn Z

    2014-01-01

    The chlorinated solvent trichloroethylene (TCE) is a ubiquitous environmental pollutant. The carcinogenic hazard of TCE was the subject of a 2012 evaluation by a Working Group of the International Agency for Research on Cancer (IARC). Information on exposures, relevant data from epidemiologic studies, bioassays in experimental animals, and toxicity and mechanism of action studies was used to conclude that TCE is carcinogenic to humans (Group 1). This article summarizes the key evidence forming the scientific bases for the IARC classification. Exposure to TCE from environmental sources (including hazardous waste sites and contaminated water) is common throughout the world. While workplace use of TCE has been declining, occupational exposures remain of concern, especially in developing countries. The strongest human evidence is from studies of occupational TCE exposure and kidney cancer. Positive, although less consistent, associations were reported for liver cancer and non-Hodgkin lymphoma. TCE is carcinogenic at multiple sites in multiple species and strains of experimental animals. The mechanistic evidence includes extensive data on the toxicokinetics and genotoxicity of TCE and its metabolites. Together, available evidence provided a cohesive database supporting the human cancer hazard of TCE, particularly in the kidney. For other target sites of carcinogenicity, mechanistic and other data were found to be more limited. Important sources of susceptibility to TCE toxicity and carcinogenicity were also reviewed by the Working Group. In all, consideration of the multiple evidence streams presented herein informed the IARC conclusions regarding the carcinogenicity of TCE. © 2013.

  9. Mechanistic and Economical Characteristics of Asphalt Rubber Mixtures

    Directory of Open Access Journals (Sweden)

    Mena I. Souliman

    2016-01-01

    Full Text Available Load associated fatigue cracking is one of the major distress types occurring in flexible pavement systems. Flexural bending beam fatigue laboratory test has been used for several decades and is considered to be an integral part of the new superpave advanced characterization procedure. One of the most significant solutions to prolong the fatigue life for an asphaltic mixture is to utilize flexible materials as rubber. A laboratory testing program was performed on a conventional and Asphalt Rubber- (AR- gap-graded mixtures to investigate the impact of added rubber on the mechanical, mechanistic, and economical attributes of asphaltic mixtures. Strain controlled fatigue tests were conducted according to American Association of State Highway and Transportation Officials (AASHTO procedures. The results from the beam fatigue tests indicated that the AR-gap-graded mixtures would have much longer fatigue life compared with the reference (conventional mixtures. In addition, a mechanistic analysis using 3D-Move software coupled with a cost analysis study based on the fatigue performance on the two mixtures was performed. Overall, analysis showed that AR modified asphalt mixtures exhibited significantly lower cost of pavement per 1000 cycles of fatigue life per mile compared to conventional HMA mixture.

  10. Centrifugal pumping of gas-liquid mixtures: a mechanistic approach

    Energy Technology Data Exchange (ETDEWEB)

    Estevam, Valdir [PETROBRAS, Rio de Janeiro, RJ (Brazil); Franca, Fernando A. [Universidade Estadual de Campinas, SP (Brazil); Alhanati, Francisco J.S. [C-Fer Technologies, Edmonton, Alberta (Canada)

    2004-07-01

    Centrifugal pumps are known to show a 'surging' behavior at certain conditions of free gas and liquid flow rate at the intake. In the 'surging region' on a pump characteristic curve, the head generated is significantly lower than if the pump were handling a gas-liquid homogeneous mixture. The surging happens, as one shows in this paper, due to the existence of a gas pocket, referred as 'elongated bubble', at the pump impeller inlet region. Therefore, to be able to predict the performance of centrifugal pumps under two-phase conditions, one has to disclose and model the mechanisms that set existence of the elongated bubble at the impeller inlet, besides calculating its length inside the impeller. This paper reports on the results of experimental and mechanistic modelling work conducted with the objective of better predicting the gas-liquid performance of centrifugal pumps under all range of conditions, including those characterized by 'surging'. The focus was on small diameter centrifugal pumps used to produce oil wells. A mechanistic two-fluid model devised to calculate the head generated by the pump was developed. The predictions of the model show good agreement with data collected for this study, and with data recently collected by other research organizations. (author)

  11. New web-based applications for mechanistic case diagramming

    Directory of Open Access Journals (Sweden)

    Fred R. Dee

    2014-07-01

    Full Text Available The goal of mechanistic case diagraming (MCD is to provide students with more in-depth understanding of cause and effect relationships and basic mechanistic pathways in medicine. This will enable them to better explain how observed clinical findings develop from preceding pathogenic and pathophysiological events. The pedagogic function of MCD is in relating risk factors, disease entities and morphology, signs and symptoms, and test and procedure findings in a specific case scenario with etiologic pathogenic and pathophysiological sequences within a flow diagram. In this paper, we describe the addition of automation and predetermined lists to further develop the original concept of MCD as described by Engelberg in 1992 and Guerrero in 2001. We demonstrate that with these modifications, MCD is effective and efficient in small group case-based teaching for second-year medical students (ratings of ~3.4 on a 4.0 scale. There was also a significant correlation with other measures of competency, with a ‘true’ score correlation of 0.54. A traditional calculation of reliability showed promising results (α =0.47 within a low stakes, ungraded environment. Further, we have demonstrated MCD's potential for use in independent learning and TBL. Future studies are needed to evaluate MCD's potential for use in medium stakes assessment or self-paced independent learning and assessment. MCD may be especially relevant in returning students to the application of basic medical science mechanisms in the clinical years.

  12. The coefficient of restitution of pressurized balls: a mechanistic model

    Science.gov (United States)

    Georgallas, Alex; Landry, Gaëtan

    2016-01-01

    Pressurized, inflated balls used in professional sports are regulated so that their behaviour upon impact can be anticipated and allow the game to have its distinctive character. However, the dynamics governing the impacts of such balls, even on stationary hard surfaces, can be extremely complex. The energy transformations, which arise from the compression of the gas within the ball and from the shear forces associated with the deformation of the wall, are examined in this paper. We develop a simple mechanistic model of the dependence of the coefficient of restitution, e, upon both the gauge pressure, P_G, of the gas and the shear modulus, G, of the wall. The model is validated using the results from a simple series of experiments using three different sports balls. The fits to the data are extremely good for P_G > 25 kPa and consistent values are obtained for the value of G for the wall material. As far as the authors can tell, this simple, mechanistic model of the pressure dependence of the coefficient of restitution is the first in the literature. *%K Coefficient of Restitution, Dynamics, Inflated Balls, Pressure, Impact Model

  13. Water on hydrophobic surfaces: Mechanistic modeling of hydrophobic interaction chromatography.

    Science.gov (United States)

    Wang, Gang; Hahn, Tobias; Hubbuch, Jürgen

    2016-09-23

    Mechanistic models are successfully used for protein purification process development as shown for ion-exchange column chromatography (IEX). Modeling and simulation of hydrophobic interaction chromatography (HIC) in the column mode has been seldom reported. As a combination of these two techniques is often encountered in biopharmaceutical purification steps, accurate modeling of protein adsorption in HIC is a core issue for applying holistic model-based process development, especially in the light of the Quality by Design (QbD) approach. In this work, a new mechanistic isotherm model for HIC is derived by consideration of an equilibrium between well-ordered water molecules and bulk-like ordered water molecules on the hydrophobic surfaces of protein and ligand. The model's capability of describing column chromatography experiments is demonstrated with glucose oxidase, bovine serum albumin (BSA), and lysozyme on Capto™ Phenyl (high sub) as model system. After model calibration from chromatograms of bind-and-elute experiments, results were validated with batch isotherms and prediction of further gradient elution chromatograms. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Trichloroethylene: Mechanistic, Epidemiologic and Other Supporting Evidence of Carcinogenic Hazard

    Science.gov (United States)

    Rusyn, Ivan; Chiu, Weihsueh A.; Lash, Lawrence H.; Kromhout, Hans; Hansen, Johnni; Guyton, Kathryn Z.

    2013-01-01

    The chlorinated solvent trichloroethylene (TCE) is a ubiquitous environmental pollutant. The carcinogenic hazard of TCE was the subject of a 2012 evaluation by a Working Group of the International Agency for Research on Cancer (IARC). Information on exposures, relevant data from epidemiologic studies, bioassays in experimental animals, and toxicity and mechanism of action studies was used to conclude that TCE is carcinogenic to humans (Group 1). This article summarizes the key evidence forming the scientific bases for the IARC classification. Exposure to TCE from environmental sources (including from hazardous waste sites and contaminated water) is common throughout the world. While workplace use of TCE has been declining, occupational exposures remain of concern, especially in developing countries. Strongest human evidence is from studies of occupational TCE exposure and kidney cancer. Positive, although less consistent, associations were reported for liver cancer and non-Hodgkin's lymphoma. TCE is carcinogenic at multiple sites in multiple species and strains of experimental animals. The mechanistic evidence includes extensive data on the toxicokinetics and genotoxicity of TCE and its metabolites. Together, available evidence provided a cohesive database supporting the human cancer hazard of TCE, particularly in the kidney. For other target sites of carcinogenicity, mechanistic and other data were found to be more limited. Important sources of susceptibility to TCE toxicity and carcinogenicity were also reviewed by the Working Group. In all, consideration of the multiple evidence streams presented herein informed the IARC conclusions regarding the carcinogenicity of TCE. PMID:23973663

  15. A Quasi-Mechanistic Mathematical Representation for Blood Viscosity

    Directory of Open Access Journals (Sweden)

    Samuel J. Hund

    2017-03-01

    Full Text Available Blood viscosity is a crucial element for any computation of flow fields in the vasculature or blood-wetted devices. Although blood is comprised of multiple elements, and its viscosity can vary widely depending on several factors, in practical applications, it is commonly assumed to be a homogeneous, Newtonian fluid with a nominal viscosity typically of 3.5 cP. Two quasi-mechanistic models for viscosity are presented here, built on the foundation of the Krieger model of suspensions, in which dependencies on shear rate, hematocrit, and plasma protein concentrations are explicitly represented. A 3-parameter Asymptotic Krieger model (AKM exhibited excellent agreement with published Couette experiments over four decades of shear rate (0–1000 s-1, root mean square (RMS error = 0.21 cP. A 5-parameter Modified Krieger Model (MKM5 also demonstrated a very good fit to the data (RMS error = 1.74 cP. These models avoid discontinuities exhibited by previous models with respect to hematocrit and shear rate. In summary, the quasi-mechanistic, Modified-Krieger Model presented here offers a reasonable compromise in complexity to provide flexibility to account for several factors that affect viscosity in practical applications, while assuring accuracy and stability.

  16. Contemporary views on human aging and longevity

    Directory of Open Access Journals (Sweden)

    Chmielewski Piotr

    2016-06-01

    Full Text Available Aging is currently stimulating intense interest of both researchers and the general public. In developed countries, the average life expectancy has increased by roughly 30 years within the last century, and human senescence has been delayed by around a decade. Although aging is arguably the most familiar aspect of human biology, its proximate and ultimate causes have not been elucidated fully and understood yet. Nowadays there are two main approaches to the ultimate causes of aging. These are deterministic and stochastic models. The proximate theories constitute a distinct group of explanations. They focus on mechanistic causes of aging. In this view, there is no reason to believe that there is only one biological mechanism responsible for aging. The aging process is highly complex and results from an accumulation of random molecular damage. Currently, the disposable soma theory (DST, proposed by Thomas Kirkwood, is the most influential and coherent line of reasoning in biogerontology. This model does not postulate any particular mechanism underpinning somatic defense. Therefore, it is compatible with various models, including mechanistic and evolutionary explanations. Recently, however, an interesting theory of hyper-function of mTOR as a more direct cause of aging has been formulated by Mikhail Blagosklonny, offering an entirely different approach to numerous problems and paradoxes in current biogerontology. In this view, aging is quasi-programmed, which means that it is an aimless continuation of developmental growth. This mTOR-centric model allows the prediction of completely new relationships. The aim of this article is to present and compare the views of both parties in the dispute, based on the results of some recent experimental studies, and the contemporary knowledge of selected major aspects of human aging and longevity

  17. A mechanistic model for the evolution of multicellularity

    Science.gov (United States)

    Amado, André; Batista, Carlos; Campos, Paulo R. A.

    2018-02-01

    Through a mechanistic approach we investigate the formation of aggregates of variable sizes, accounting mechanisms of aggregation, dissociation, death and reproduction. In our model, cells can produce two metabolites, but the simultaneous production of both metabolites is costly in terms of fitness. Thus, the formation of larger groups can favor the aggregates to evolve to a configuration where division of labor arises. It is assumed that the states of the cells in a group are those that maximize organismal fitness. In the model it is considered that the groups can grow linearly, forming a chain, or compactly keeping a roughly spherical shape. Starting from a population consisting of single-celled organisms, we observe the formation of groups with variable sizes and usually much larger than two-cell aggregates. Natural selection can favor the formation of large groups, which allows the system to achieve new and larger fitness maxima.

  18. Mechanistic modelling of genetic and epigenetic events in radiation carcinogenesis

    International Nuclear Information System (INIS)

    Andreev, S. G.; Eidelman, Y. A.; Salnikov, I. V.; Khvostunov, I. K.

    2006-01-01

    Methodological problems arise on the way of radiation carcinogenesis modelling with the incorporation of radiobiological and cancer biology mechanistic data. The results of biophysical modelling of different endpoints [DNA DSB induction, repair, chromosome aberrations (CA) and cell proliferation] are presented and applied to the analysis of RBE-LET relationships for radiation-induced neoplastic transformation (RINT) of C3H/10T1/2 cells in culture. Predicted values for some endpoints correlate well with the data. It is concluded that slowly repaired DSB clusters, as well as some kind of CA, may be initiating events for RINT. As an alternative interpretation, it is possible that DNA damage can induce RINT indirectly via epigenetic process. A hypothetical epigenetic pathway for RINT is discussed. (authors)

  19. Mechanistic failure mode investigation and resolution of parvovirus retentive filters.

    Science.gov (United States)

    LaCasse, Daniel; Lute, Scott; Fiadeiro, Marcus; Basha, Jonida; Stork, Matthew; Brorson, Kurt; Godavarti, Ranga; Gallo, Chris

    2016-07-08

    Virus retentive filters are a key product safety measure for biopharmaceuticals. A simplistic perception is that they function solely based on a size-based particle removal mechanism of mechanical sieving and retention of particles based on their hydrodynamic size. Recent observations have revealed a more nuanced picture, indicating that changes in viral particle retention can result from process pressure and/or flow interruptions. In this study, a mechanistic investigation was performed to help identify a potential mechanism leading to the reported reduced particle retention in small virus filters. Permeate flow rate or permeate driving force were varied and analyzed for their impact on particle retention in three commercially available small virus retentive filters. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:959-970, 2016. © 2016 American Institute of Chemical Engineers.

  20. Serum Albumin Binding and Esterase Activity: Mechanistic Interactions with Organophosphates

    Directory of Open Access Journals (Sweden)

    Nikolay V. Goncharov

    2017-07-01

    Full Text Available The albumin molecule, in contrast to many other plasma proteins, is not covered with a carbohydrate moiety and can bind and transport various molecules of endogenous and exogenous origin. The enzymatic activity of albumin, the existence of which many scientists perceive skeptically, is much less studied. In toxicology, understanding the mechanistic interactions of organophosphates with albumin is a special problem, and its solution could help in the development of new types of antidotes. In the present work, the history of the issue is briefly examined, then our in silico data on the interaction of human serum albumin with soman, as well as comparative in silico data of human and bovine serum albumin activities in relation to paraoxon, are presented. Information is given on the substrate specificity of albumin and we consider the possibility of its affiliation to certain classes in the nomenclature of enzymes.

  1. Mechanistic modelling of the drying behaviour of single pharmaceutical granules

    DEFF Research Database (Denmark)

    Thérèse F.C. Mortier, Séverine; Beer, Thomas De; Gernaey, Krist

    2012-01-01

    The trend to move towards continuous production processes in pharmaceutical applications enhances the necessity to develop mechanistic models to understand and control these processes. This work focuses on the drying behaviour of a single wet granule before tabletting, using a six......-segmented fluidised bed drying system, which is part of a fully continuous from-powder-to-tablet manufacturing line. The drying model is based on a model described by Mezhericher et al. [1] and consists of two submodels. In the first drying phase (submodel 1), the surface water evaporates, while in the second drying...... phase (submodel 2), the water inside the granule evaporates. The second submodel contains an empirical power coefficient, b. A sensitivity analysis was performed to study the influence of parameters on the moisture content of single pharmaceutical granules, which clearly points towards the importance...

  2. Mechanistic characterization of chloride interferences in electrothermal atomization systems

    Science.gov (United States)

    Shekiro, J.M.; Skogerboe, R.K.; Taylor, Howard E.

    1988-01-01

    A computer-controlled spectrometer with a photodiode array detector has been used for wavelength and temperature resolved characterization of the vapor produced by an electrothermal atomizer. The system has been used to study the chloride matrix interference on the atomic absorption spectrometric determination of manganese and copper. The suppression of manganese and copper atom populations by matrix chlorides such as those of calcium and magnesium is due to the gas-phase formation of an analyte chloride species followed by the diffusion of significant fractions of these species from the atom cell prior to completion of the atomization process. The analyte chloride species cannot be formed when matrix chlorides with metal-chloride bond dissociation energies above those of the analyte chlorides are the principal entitles present. The results indicate that multiple wavelength spectrometry used to obtain temperature-resolved spectra is a viable tool in the mechanistic characterization of interference effects observed with electrothermal atomization systems. ?? 1988 American Chemical Society.

  3. Synthetic and mechanistic aspects of titanium-mediated carbonyl olefinations

    Energy Technology Data Exchange (ETDEWEB)

    Petasis, N.A.; Staszewski, J.P.; Hu, Yong-Han; Lu, Shao-Po [Univ. of Southern California, Los Angeles, CA (United States)

    1995-12-31

    A new method for the olefination of carbonyl compounds with dimethyl titanocene, and other related bishydrocarbyl titanocene derivatives has been recently developed in the author`s laboratories. This process is experimentally convenient and works with various types of carbonyl compounds, including aldehydes, ketones, esters, lactones, carbonates, anhydrides, amides, imides, lactams, thioesters, selenoesters, and acylsilanes. More recent studies have focused on the scope and utility of this reaction, including mechanistic studies and synthetic applications. In addition to varying the reaction conditions, the authors have examined several mixed titanocene derivatives and have found ways for carrying out this type of olefination at room temperature, such as the use of tris(trimethylsilyl) titanacyclobutene. The authors have also employed this reaction in the modification of carbohydrates and cyclobutenediones. This olefination was also followed-up with subsequent transformations to produce carbocycles and heterocycles, including tetrahydrofurans and tetrahydropyrans.

  4. Antioxidative activity of caffeic acid: Mechanistic DFT study

    Directory of Open Access Journals (Sweden)

    Redžepović Izudin

    2017-01-01

    Full Text Available This paper reports the results of comprehensive mechanistic investigations of the hydrogen atom transfer (HAT, radical adduct formation (RAF, single electron transfer – proton transfer (SET-PT, and sequential proton loss electron transfer (SPLET mechanisms of caffeic acid (CA. The goals of the work were achieved by simulating the reactions of CA with hydroxyl radical in benzene and water solutions. It was found that SET-PT is not a favourable antioxidative mechanism of CA. On the other hand, HAT and RAF are competitive, because HAT pathways yield thermodynamically more stable radical products, and RAF pathways require smaller activation barriers. In polar basic environment SPLET is a probable antioxidative mechanism of CA, with exceptionally large rate.

  5. Toxic neuropathies: Mechanistic insights based on a chemical perspective.

    Science.gov (United States)

    LoPachin, Richard M; Gavin, Terrence

    2015-06-02

    2,5-Hexanedione (HD) and acrylamide (ACR) are considered to be prototypical among chemical toxicants that cause central-peripheral axonopathies characterized by distal axon swelling and degeneration. Because the demise of distal regions was assumed to be causally related to the onset of neurotoxicity, substantial effort was devoted to deciphering the respective mechanisms. Continued research, however, revealed that expression of the presumed hallmark morphological features was dependent upon the daily rate of toxicant exposure. Indeed, many studies reported that the corresponding axonopathic changes were late developing effects that occurred independent of behavioral and/or functional neurotoxicity. This suggested that the toxic axonopathy classification might be based on epiphenomena related to dose-rate. Therefore, the goal of this mini-review is to discuss how quantitative morphometric analyses and the establishment of dose-dependent relationships helped distinguish primary, mechanistically relevant toxicant effects from non-specific consequences. Perhaps more importantly, we will discuss how knowledge of neurotoxicant chemical nature can guide molecular-level research toward a better, more rational understanding of mechanism. Our discussion will focus on HD, the neurotoxic γ-diketone metabolite of the industrial solvents n-hexane and methyl-n-butyl ketone. Early investigations suggested that HD caused giant neurofilamentous axonal swellings and eventual degeneration in CNS and PNS. However, as our review will point out, this interpretation underwent several iterations as the understanding of γ-diketone chemistry improved and more quantitative experimental approaches were implemented. The chemical concepts and design strategies discussed in this mini-review are broadly applicable to the mechanistic studies of other chemicals (e.g., n-propyl bromine, methyl methacrylate) that cause toxic neuropathies. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  6. Parameter and uncertainty estimation for mechanistic, spatially explicit epidemiological models

    Science.gov (United States)

    Finger, Flavio; Schaefli, Bettina; Bertuzzo, Enrico; Mari, Lorenzo; Rinaldo, Andrea

    2014-05-01

    Epidemiological models can be a crucially important tool for decision-making during disease outbreaks. The range of possible applications spans from real-time forecasting and allocation of health-care resources to testing alternative intervention mechanisms such as vaccines, antibiotics or the improvement of sanitary conditions. Our spatially explicit, mechanistic models for cholera epidemics have been successfully applied to several epidemics including, the one that struck Haiti in late 2010 and is still ongoing. Calibration and parameter estimation of such models represents a major challenge because of properties unusual in traditional geoscientific domains such as hydrology. Firstly, the epidemiological data available might be subject to high uncertainties due to error-prone diagnosis as well as manual (and possibly incomplete) data collection. Secondly, long-term time-series of epidemiological data are often unavailable. Finally, the spatially explicit character of the models requires the comparison of several time-series of model outputs with their real-world counterparts, which calls for an appropriate weighting scheme. It follows that the usual assumption of a homoscedastic Gaussian error distribution, used in combination with classical calibration techniques based on Markov chain Monte Carlo algorithms, is likely to be violated, whereas the construction of an appropriate formal likelihood function seems close to impossible. Alternative calibration methods, which allow for accurate estimation of total model uncertainty, particularly regarding the envisaged use of the models for decision-making, are thus needed. Here we present the most recent developments regarding methods for parameter and uncertainty estimation to be used with our mechanistic, spatially explicit models for cholera epidemics, based on informal measures of goodness of fit.

  7. The challenge of making ozone risk assessment for forest trees more mechanistic

    International Nuclear Information System (INIS)

    Matyssek, R.; Sandermann, H.; Wieser, G.; Booker, F.; Cieslik, S.; Musselman, R.; Ernst, D.

    2008-01-01

    Upcoming decades will experience increasing atmospheric CO 2 and likely enhanced O 3 exposure which represents a risk for the carbon sink strength of forests, so that the need for cause-effect related O 3 risk assessment increases. Although assessment will gain in reliability on an O 3 uptake basis, risk is co-determined by the effective dose, i.e. the plant's sensitivity per O 3 uptake. Recent progress in research on the molecular and metabolic control of the effective O 3 dose is reported along with advances in empirically assessing O 3 uptake at the whole-tree and stand level. Knowledge on both O 3 uptake and effective dose (measures of stress avoidance and tolerance, respectively) needs to be understood mechanistically and linked as a pre-requisite before practical use of process-based O 3 risk assessment can be implemented. To this end, perspectives are derived for validating and promoting new O 3 flux-based modelling tools. - Clarifying and linking mechanisms of O 3 uptake and effective dose are research challenges highlighted in view of recent progress and perspectives towards cause-effect based risk assessment

  8. Influence of field attack by carrot psyllid (Trioza apicalis Förster) on sensory quality, antioxidant capacity and content of terpenes, falcarindiol and 6-methoxymellein of carrots (Daucus carota L.).

    Science.gov (United States)

    Seljåsen, Randi; Vogt, Gjermund; Olsen, Elisabeth; Lea, Per; Høgetveit, Lars Arne; Tajet, Torgeir; Meadow, Richard; Bengtsson, Gunnar B

    2013-03-20

    The effect of different degrees of attack by carrot psyllid (Trioza apicalis) on quality parameters of carrots was studied in field experiments for two years. Treatments were different degrees of physical insect protection by floating row cover. An increasing attack level of psyllids showed an enhancement effect on the antioxidant capacity (ORAC), content of falcarindiol, 6-methoxymellein, and terpenes, and scores for bitter taste, chemical flavor, terpene flavor, and toughness. Carrot psyllid attack decreased the yield, total sugar, fructose, glucose, and sensory attributes sweet taste, color hue, color strength, crispiness, and juiciness. Carrot plants at 8-10 weeks of age tolerated attack by psyllids at low levels (2% leaves with curling or discoloration).

  9. The overcoming of the mechanistic framework in Planck's research around 1900: a comparison with Boltzmann', Wien' and Rayleigh's contributions

    International Nuclear Information System (INIS)

    Baracca, A.; Renn, Juergen

    2008-01-01

    It will argue in this talk that the main Planck's merit in 1900 was the overcoming of a mechanist and reductionist horizon, while the effective introduction of the 'quantum', as a physical entity, is very doubtful. On the one hand, Planck maintained an absolute conception of the laws of thermodynamics, and did not accept Boltzmann's probabilistic, and reductionist view (as he declared in his Authobiography, and indirectly appears from Zermelo's paper). On the other hand, the formula known as 'Rayleigh's law' for the spectrum of the cavity radiation was not proposed at all in 1900 (nor later on, as a general expression of the spectrum), and in any case Rayliegh's had absolutely no influence on Planck. We will discuss the early 1900 purely thermodynamical derivation of Planck's law, and his subsequent exploitment of Boltzmann's probabilistic treatment, with the 'discretization' procedure, in the 'act of desesperation' in order to justify his result

  10. A pact with the embryo: Viktor Hamburger, holistic and mechanistic philosophy in the development of neuroembryology, 1927-1955.

    Science.gov (United States)

    Allen, Garland E

    2004-01-01

    Viktor Hamburger was a developmental biologist interested in the ontogenesis of hte vertebrate nervous system. A student of Hans Spemann at Freiburg in the 1920s, Hamburger picked up a holistic view of the embryo that precluded him from treating it in a reductionist way; at the same time, he was committed to a materialist and analytical approach that eschewed any form of vitalism or metaphysics. This paper explores how Hamburger walked this thin line between mechanistic reductionism and metaphysical vitalism in light of his work on the factors influencing growth of neurons into limb buds, and the discovery of nerve growth factor, work carried out with Rita Levi-Montalcini and Stanley Cohen.

  11. Proceedings of the international workshop on mechanistic understanding of radionuclide migration in compacted/intact systems

    International Nuclear Information System (INIS)

    Tachi, Yukio; Yui, Mikazu

    2010-03-01

    The international workshop on mechanistic understanding of radionuclide migration in compacted / intact systems was held at ENTRY, JAEA, Tokai on 21st - 23rd January, 2009. This workshop was hosted by Japan Atomic Energy Agency (JAEA) as part of the project on the mechanistic model/database development for radionuclide sorption and diffusion behavior in compacted / intact systems. The overall goal of the project is to develop the mechanistic model / database for a consistent understanding and prediction of migration parameters and its uncertainties for performance assessment of geological disposal of radioactive waste. The objective of the workshop is to integrate the state-of-the-art of mechanistic sorption and diffusion model in compacted / intact systems, especially in bentonite / clay systems, and discuss the JAEA's mechanistic approaches and future challenges, especially the following discussions points; 1) What's the status and difficulties for mechanistic model/database development? 2) What's the status and difficulties for applicability of mechanistic model to the compacted/intact system? 3) What's the status and difficulties for obtaining evidences for mechanistic model? 4) What's the status and difficulties for standardization of experimental methodology for batch sorption and diffusion? 5) What's the uncertainties of transport parameters in radionuclides migration analysis due to a lack of understanding/experimental methodologies, and how do we derive them? This report includes workshop program, overview and materials of each presentation, summary of discussions. (author)

  12. Application of mechanistic models to fermentation and biocatalysis for next-generation processes

    DEFF Research Database (Denmark)

    Gernaey, Krist; Eliasson Lantz, Anna; Tufvesson, Pär

    2010-01-01

    Mechanistic models are based on deterministic principles, and recently, interest in them has grown substantially. Herein we present an overview of mechanistic models and their applications in biotechnology, including future perspectives. Model utility is highlighted with respect to selection of v...

  13. A formal, one-pot β-chlorination of primary alcohols and its utilization in the transformation of terpene feedstock and the synthesis of a C2-symmetrical terminal bis-epoxide.

    Science.gov (United States)

    Swatschek, Jörg; Grothues, Lydia; Bauer, Jonathan O; Strohmann, Carsten; Christmann, Mathias

    2014-02-07

    A one-pot transformation of alkan-1-ols into 2-chloroalkan-1-ols is described. As a practical application, terpene-derived primary alcohols were converted into semiochemicals such as olfactory lactones (aerangis lactone, whisky lactone, and cognac lactone) and pheromones (cruentol and ferrugineol). Using heptane-1,7-diol as a bifunctional substrate, the corresponding bis-epoxide was synthesized by bidirectional synthesis in good yield and high enantioselectivity.

  14. Induction of furano-terpene production and formation of the enzyme system from mevalonate to isopentenyl pyrophosphate in sweet potato root tissue injured by Ceratocystis fimbriata and by toxic chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Oba, K.; Tatematsu, H.; Yamashita, K.; Uritani, I.

    1976-07-01

    When sweet potato (Ipomoea batatas) root tissue was infected by Ceratocystis fimbriata, activity of the enzyme system from mevalonate to isopentenyl pyrophosphate, especially of pyrophosphomevalonate decarboxylase (EC 4.1.1.33), was increased in the noninfected tissue adjacent to the infected region, preceding the furano-terpene production in the infected region. Cutting and incubation of sweet potato slices did not produce furano-terpenes, and only slightly increased the activity of the enzyme system from mevalonate to isopentenyl pyrophosphate. The enzymic activity in diseased tissue was localized in the soluble fraction, and was higher in the tissue from the surface to a depth of about 5 mm with gradual decrease toward the inner part. Mercuric chloride (0.1%, w/v) and sodium dodecyl sulfate (1.0%, w/v) were utilized as model inducers of furano-terpenes and pyrophosphomevalonate decarboxylase. The mercuric chloride- or sodium dodecyl sulfate-induced response was inhibited by administration of cycloheximide to the discs together with the inducer immediately after disc preparation. When cycloheximide or blasticidin S was applied together with the inducer, to the discs 9 hours or more after disc preparation, the induction was not inhibited but rather stimulated.

  15. Modeling Bird Migration under Climate Change: A Mechanistic Approach

    Science.gov (United States)

    Smith, James A.

    2009-01-01

    How will migrating birds respond to changes in the environment under climate change? What are the implications for migratory success under the various accelerated climate change scenarios as forecast by the Intergovernmental Panel on Climate Change? How will reductions or increased variability in the number or quality of wetland stop-over sites affect migratory bird species? The answers to these questions have important ramifications for conservation biology and wildlife management. Here, we describe the use of continental scale simulation modeling to explore how spatio-temporal changes along migratory flyways affect en-route migration success. We use an individually based, biophysical, mechanistic, bird migration model to simulate the movement of shorebirds in North America as a tool to study how such factors as drought and wetland loss may impact migratory success and modify migration patterns. Our model is driven by remote sensing and climate data and incorporates important landscape variables. The energy budget components of the model include resting, foraging, and flight, but presently predation is ignored. Results/Conclusions We illustrate our model by studying the spring migration of sandpipers through the Great Plains to their Arctic breeding grounds. Why many species of shorebirds have shown significant declines remains a puzzle. Shorebirds are sensitive to stop-over quality and spacing because of their need for frequent refueling stops and their opportunistic feeding patterns. We predict bird "hydrographs that is, stop-over frequency with latitude, that are in agreement with the literature. Mean stop-over durations predicted from our model for nominal cases also are consistent with the limited, but available data. For the shorebird species simulated, our model predicts that shorebirds exhibit significant plasticity and are able to shift their migration patterns in response to changing drought conditions. However, the question remains as to whether this

  16. A new mechanistic framework to predict OCS fluxes from soils

    Science.gov (United States)

    Ogée, Jérôme; Sauze, Joana; Kesselmeier, Jürgen; Genty, Bernard; Van Diest, Heidi; Launois, Thomas; Wingate, Lisa

    2016-04-01

    Estimates of photosynthetic and respiratory fluxes at large scales are needed to improve our predictions of the current and future global CO2 cycle. Carbonyl sulfide (OCS) is the most abundant sulfur gas in the atmosphere and has been proposed as a new tracer of photosynthetic gross primary productivity (GPP), as the uptake of OCS from the atmosphere is dominated by the activity of carbonic anhydrase (CA), an enzyme abundant in leaves that also catalyses CO2 hydration during photosynthesis. However soils also exchange OCS with the atmosphere, which complicates the retrieval of GPP from atmospheric budgets. Indeed soils can take up large amounts of OCS from the atmosphere as soil microorganisms also contain CA, and OCS emissions from soils have been reported in agricultural fields or anoxic soils. To date no mechanistic framework exists to describe this exchange of OCS between soils and the atmosphere, but empirical results, once upscaled to the global scale, indicate that OCS consumption by soils dominates OCS emission and its contribution to the atmospheric budget is large, at about one third of the OCS uptake by vegetation, also with a large uncertainty. Here, we propose a new mechanistic model of the exchange of OCS between soils and the atmosphere that builds on our knowledge of soil CA activity from CO2 oxygen isotopes. In this model the OCS soil budget is described by a first-order reaction-diffusion-production equation, assuming that the hydrolysis of OCS by CA is total and irreversible. Using this model we are able to explain the observed presence of an optimum temperature for soil OCS uptake and show how this optimum can shift to cooler temperatures in the presence of soil OCS emission. Our model can also explain the observed optimum with soil moisture content previously described in the literature as a result of diffusional constraints on OCS hydrolysis. These diffusional constraints are also responsible for the response of OCS uptake to soil weight and

  17. On the antibacterial effects of manuka honey: mechanistic insights

    Directory of Open Access Journals (Sweden)

    Roberts AEL

    2015-10-01

    Full Text Available Aled Edward Lloyd Roberts,* Helen Louise Brown,* Rowena Eleri Jenkins Department of Biomedical Sciences, Cardiff Metropolitan University, Cardiff, Wales, UK *These authors contributed equally to this work Abstract: Antimicrobial resistance (AMR is an increasing clinical problem precipitated by the inappropriate use of antibiotics in the later parts of the 20th Century. This problem, coupled with the lack of novel therapeutics in the development pipeline, means AMR is reaching crisis point, with an expected annual death rate of ten million people worldwide by 2050. To reduce, and to potentially remedy this problem, many researchers are looking into natural compounds with antimicrobial and/or antivirulence activity. Manuka honey is an ancient antimicrobial remedy with a good track record against a wide range of nosocomial pathogens that have increased AMR. Its inhibitory effects are the result of its constituent components, which add varying degrees of antimicrobial efficacy to the overall activity of manuka honey. The antimicrobial efficacy of manuka honey and some of its constituent components (such as methylglyoxal and leptosperin are known to bestow some degree of antimicrobial efficacy to manuka honey. Despite growing in vitro evidence of its antimicrobial efficacy, the in vivo use of manuka honey (especially in a clinical environment has been unexpectedly slow, partly due to the lack of mechanistic data. The mechanism by which manuka honey achieves its inhibitory efficacy has recently been identified against Staphylococcus aureus and Pseudomonas aeruginosa, with both of these contrasting organisms being inhibited through different mechanisms. Manuka honey inhibits S. aureus by interfering with the cell division process, whereas P. aeruginosa cells lyse in its presence due to the reduction of a key structural protein. In addition to these inhibitory effects, manuka honey is known to reduce virulence, motility, and biofilm formation. With this

  18. The workplace window view

    DEFF Research Database (Denmark)

    Lottrup, Lene Birgitte Poulsen; Stigsdotter, Ulrika K.; Meilby, Henrik

    2015-01-01

    Office workers’ job satisfaction and ability to work are two important factors for the viability and competitiveness of most companies, and existing studies in contexts other than workplaces show relationships between a view of natural elements and, for example, student performance...... and neighbourhood satisfaction. This study investigates whether relationships between window view, and work ability and job satisfaction also exist in the context of the workplace by focusing on office workers’ view satisfaction. The results showed that a view of natural elements was related to high view...... satisfaction, and that high view satisfaction was related to high work ability and high job satisfaction. Furthermore, the results indicated that job satisfaction mediated the effect of view satisfaction on work ability. These findings show that a view of a green outdoor environment at the workplace can...

  19. Volatile profiles of Italian monovarietal extra virgin olive oils via HS-SPME-GC-MS: newly identified compounds, flavors molecular markers, and terpenic profile.

    Science.gov (United States)

    Cecchi, Teresa; Alfei, Barbara

    2013-12-01

    This study aims to contribute to the knowledge of the commercial, sensory, and analytical characteristics of extra virgin olive oil (EVOO) from Italy (Marche region), renowned since ancient times. Headspace solid-phase micro-extraction (HS-SPME) was applied for the very first time to the sampling of volatile compounds of eleven typical Italian monocultivar EVOOs. Forty-eight compounds were characterised by GC-MS, some of them were only occasionally found in other EVOOs and some other were never detected before in any EVOO. Compounds belonging mainly to alcohols, esters, aldehydes, ketones and hydrocarbons chemical classes characterised the volatile profiles. The main volatile compounds detected in the EVOOs were the C6 compounds derived from polyunsaturated fatty acids, through the lipoxygenase pathway, in different proportion according to the specific cultivar. The results suggest that genetic factors strongly influence volatile formation and terpene hydrocarbons are claimed to be suitable markers of the geographic origin and genotype of the EVOO. Correlations among sensory attributes evaluated by a panel test and the presence of specific volatile compounds were highlighted for the very first time. The significance of the presence of some newly identified volatile compounds was discussed. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Mechanistic studies of ethylene biosynthesis in higher plants

    International Nuclear Information System (INIS)

    McGeehan, G.M.

    1986-01-01

    Ethylene is a plant hormone that elicits a wide variety of responses in plant tissue. Among these responses are the hastening of abscission, ripening and senescence. In 1979 it was discovered that 1-amino-1-cyclopropane carboxylic acid is the immediate biosynthetic precursor to ethylene. Given the obvious economic significance of ethylene production the authors concentrated their studies on the conversion of ACC to ethylene. They delved into mechanistic aspects of ACC oxidation and they studied potential inhibitors of ethylene forming enzyme (EFE). They synthesized various analogs of ACC and found that EFE shows good stereodiscrimination among alkyl substituted ACC analogs with the 1R, 2S stereoisomer being processed nine times faster than the 1S, 2R isomer in the MeACC series. They also synthesized 2-cyclopropyl ACC which is a good competitive inhibitor of EFE. This compound also causes time dependent loss of EFE activity leading us to believe it is an irreversible inhibitor of ethylene formation. The synthesis of these analogs has also allowed them to develop a spectroscopic technique to assign the relative stereochemistry of alkyl groups. 13 C NMR allows them to assign the alkyl stereochemistry based upon gamma-shielding effects on the carbonyl resonance. Lastly, they measured kinetic isotope effects on the oxidation of ACC in vivo and in vitro and found that ACC is oxidized by a rate-determining 1-electron removal from nitrogen in close accord with mechanisms for the oxidation of other alkyl amines

  1. Ancient Chinese medicine and mechanistic evidence of acupuncture physiology.

    Science.gov (United States)

    Yang, Edward S; Li, Pei-Wen; Nilius, Bernd; Li, Geng

    2011-11-01

    Acupuncture has been widely used in China for three millennia as an art of healing. Yet, its physiology is not yet understood. The current interest in acupuncture started in 1971. Soon afterward, extensive research led to the concept of neural signaling with possible involvement of opioid peptides, glutamate, adenosine and identifying responsive parts in the central nervous system. In the last decade scientists began investigating the subject with anatomical and molecular imaging. It was found that mechanical movements of the needle, ignored in the past, appear to be central to the method and intracellular calcium ions may play a pivotal role. In this review, we trace the technique of clinical treatment from the first written record about 2,200 years ago to the modern time. The ancient texts have been used to introduce the concepts of yin, yang, qi, de qi, and meridians, the traditional foundation of acupuncture. We explore the sequence of the physiological process, from the turning of the needle, the mechanical wave activation of calcium ion channel to beta-endorphin secretion. By using modern terminology to re-interpret the ancient texts, we have found that the 2nd century B.C.: physiologists were meticulous investigators and their explanation fits well with the mechanistic model derived from magnetic resonance imaging (MRI) and confocal microscopy. In conclusion, the ancient model appears to have withstood the test of time surprisingly well confirming the popular axiom that the old wine is better than the new.

  2. A brief review of exercise, bipolar disorder, and mechanistic pathways

    Science.gov (United States)

    Thomson, Daniel; Turner, Alyna; Lauder, Sue; Gigler, Margaret E.; Berk, Lesley; Singh, Ajeet B.; Pasco, Julie A.; Berk, Michael; Sylvia, Louisa

    2015-01-01

    Despite evidence that exercise has been found to be effective in the treatment of depression, it is unclear whether these data can be extrapolated to bipolar disorder. Available evidence for bipolar disorder is scant, with no existing randomized controlled trials having tested the impact of exercise on depressive, manic or hypomanic symptomatology. Although exercise is often recommended in bipolar disorder, this is based on extrapolation from the unipolar literature, theory and clinical expertise and not empirical evidence. In addition, there are currently no available empirical data on program variables, with practical implications on frequency, intensity and type of exercise derived from unipolar depression studies. The aim of the current paper is to explore the relationship between exercise and bipolar disorder and potential mechanistic pathways. Given the high rate of medical co-morbidities experienced by people with bipolar disorder, it is possible that exercise is a potentially useful and important intervention with regard to general health benefits; however, further research is required to elucidate the impact of exercise on mood symptomology. PMID:25788889

  3. Mechanistic modeling of insecticide risks to breeding birds in ...

    Science.gov (United States)

    Insecticide usage in the United States is ubiquitous in urban, suburban, and rural environments. In evaluating data for an insecticide registration application and for registration review, scientists at the United States Environmental Protection Agency (USEPA) assess the fate of the insecticide and the risk the insecticide poses to the environment and non-target wildlife. At the present time, current USEPA risk assessments do not include population-level endpoints. In this paper, we present a new mechanistic model, which allows risk assessors to estimate the effects of insecticide exposure on the survival and seasonal productivity of birds known to use agricultural fields during their breeding season. The new model was created from two existing USEPA avian risk assessment models, the Terrestrial Investigation Model (TIM v.3.0) and the Markov Chain Nest Productivity model (MCnest). The integrated TIM/MCnest model has been applied to assess the relative risk of 12 insecticides used to control corn pests on a suite of 31 avian species known to use cornfields in midwestern agroecosystems. The 12 insecticides that were assessed in this study are all used to treat major pests of corn (corn root worm borer, cutworm, and armyworm). After running the integrated TIM/MCnest model, we found extensive differences in risk to birds among insecticides, with chlorpyrifos and malathion (organophosphates) generally posing the greatest risk, and bifenthrin and ë-cyhalothrin (

  4. Mechanistic Perspectives of Maslinic Acid in Targeting Inflammation

    Directory of Open Access Journals (Sweden)

    Wei Hsum Yap

    2015-01-01

    Full Text Available Chronic inflammation drives the development of various pathological diseases such as rheumatoid arthritis, atherosclerosis, multiple sclerosis, and cancer. The arachidonic acid pathway represents one of the major mechanisms for inflammation. Prostaglandins (PGs are lipid products generated from arachidonic acid by the action of cyclooxygenase (COX enzymes and their activity is blocked by nonsteroidal anti-inflammatory drugs (NSAIDS. The use of natural compounds in regulation of COX activity/prostaglandins production is receiving increasing attention. In Mediterranean diet, olive oil and table olives contain significant dietary sources of maslinic acid. Maslinic acid is arising as a safe and novel natural pentacyclic triterpene which has protective effects against chronic inflammatory diseases in various in vivo and in vitro experimental models. Understanding the anti-inflammatory mechanism of maslinic acid is crucial for its development as a potential dietary nutraceutical. This review focuses on the mechanistic action of maslinic acid in regulating the inflammation pathways through modulation of the arachidonic acid metabolism including the nuclear factor-kappa B (NF-κB/COX-2 expression, upstream protein kinase signaling, and phospholipase A2 enzyme activity. Further investigations may provide insight into the mechanism of maslinic acid in regulating the molecular targets and their associated pathways in response to specific inflammatory stimuli.

  5. Study of zircaloy corrosion to develop mechanistic understanding

    International Nuclear Information System (INIS)

    Ortner, S.; Swan, H.; Laferrere, A.; English, C.; Hyde, J.; Styman, P.; Jurkschat, K.; Hulme, H.; Pantelli, A.; Gass, M.; Allen, V.; Frankel, P.

    2015-01-01

    Predictions for the corrosion behaviour of Zircaloy cladding are based on empirical models. This results in significant uncertainties for forecasts beyond existing data e.g. for high burn-up, or when there has been a change in operating conditions. To allow for a more accurate prediction of corrosion behaviour a better understanding of the mechanisms involved is required. A program has been initiated with the aim of developing a detailed mechanistic understanding of out-of-pile Zircaloy corrosion behaviour. This paper reports the results of isothermal exposures of Zircaloy-4 to PWR water at 350 Celsius degrees. A variety of analytical techniques have been employed to analyse the corroded specimens, including scanning and transmission electron microscopy, atom probe tomography, micro-beam synchrotron X-ray diffraction and electron energy loss spectroscopy. When the results of these techniques are compared, it becomes evident that the periodic transition from slow to fast oxidation rates results from the accumulation of stress relief processes in the metal (particularly plastic deformation, but also oxygen and hydrogen dissolution); at the metal-oxide interface (decomposition of the flat interface into undulations); and in the oxide (cracking). These reduce the in-plane compressive stresses near the metal-oxide interface but ultimately balance them with in-plane tensile stresses which encourage through-thickness cracking, and the percolation of the environment to the metal-oxide interface. This is noticed only if allowance is made for out-of-plane stresses in the thin oxide. (authors)

  6. Diffusion theory in biology: a relic of mechanistic materialism.

    Science.gov (United States)

    Agutter, P S; Malone, P C; Wheatley, D N

    2000-01-01

    Diffusion theory explains in physical terms how materials move through a medium, e.g. water or a biological fluid. There are strong and widely acknowledged grounds for doubting the applicability of this theory in biology, although it continues to be accepted almost uncritically and taught as a basis of both biology and medicine. Our principal aim is to explore how this situation arose and has been allowed to continue seemingly unchallenged for more than 150 years. The main shortcomings of diffusion theory will be briefly reviewed to show that the entrenchment of this theory in the corpus of biological knowledge needs to be explained, especially as there are equally valid historical grounds for presuming that bulk fluid movement powered by the energy of cell metabolism plays a prominent note in the transport of molecules in the living body. First, the theory's evolution, notably from its origins in connection with the mechanistic materialist philosophy of mid nineteenth century physiology, is discussed. Following this, the entrenchment of the theory in twentieth century biology is analyzed in relation to three situations: the mechanism of oxygen transport between air and mammalian tissues; the structure and function of cell membranes; and the nature of the intermediary metalbolism, with its implicit presumptions about the intracellular organization and the movement of molecules within it. In our final section, we consider several historically based alternatives to diffusion theory, all of which have their precursors in nineteenth and twentieth century philosophy of science.

  7. Neutron structure and mechanistic studies of diisopropyl fluorophosphatase (DFPase)

    International Nuclear Information System (INIS)

    Chen, Julian C.-H.; Mustyakimov, Marat; Schoenborn, Benno P.; Langan, Paul; Blum, Marc-Michael

    2010-01-01

    The structure and mechanism of diisopropyl fluorophosphatase (DFPase) have been studied using a variety of methods, including isotopic labelling, X-ray crystallography and neutron crystallography. The neutron structure of DFPase, mechanistic studies and subsequent rational design efforts are described. Diisopropyl fluorophosphatase (DFPase) is a calcium-dependent phosphotriesterase that acts on a variety of highly toxic organophosphorus compounds that act as inhibitors of acetylcholinesterase. The mechanism of DFPase has been probed using a variety of methods, including isotopic labelling, which demonstrated the presence of a phosphoenzyme intermediate in the reaction mechanism. In order to further elucidate the mechanism of DFPase and to ascertain the protonation states of the residues and solvent molecules in the active site, the neutron structure of DFPase was solved at 2.2 Å resolution. The proposed nucleophile Asp229 is deprotonated, while the active-site solvent molecule W33 was identified as water and not hydroxide. These data support a mechanism involving direct nucleophilic attack by Asp229 on the substrate and rule out a mechanism involving metal-assisted water activation. These data also allowed for the re-engineering of DFPase through rational design to bind and productively orient the more toxic S P stereoisomers of the nerve agents sarin and cyclosarin, creating a modified enzyme with enhanced overall activity and significantly increased detoxification properties

  8. Mechanistic Modeling of Water Replenishment Rate of Zeer Refrigerator

    Directory of Open Access Journals (Sweden)

    B. N. Nwankwojike

    2017-06-01

    Full Text Available A model for predicting the water replenishment rate of zeer pot refrigerator was developed in this study using mechanistic modeling approach and evaluated at Obowo, Imo State, Nigeria using six fruits, tomatoes, guava, okra, banana, orange and avocado pear. The developed model confirmed zeer pot water replenishment rate as a function of ambient temperature, relative humidity, wind speed, thermal conductivity of the pot materials and sand, density of air and water vapor, permeability coefficient of clay and heat transfer coefficient of water into air, circumferential length, height of pot, geometrical profile of the pot, heat load of the food preserved, heat flow into the device and gradient at which the pot is placed above ground level. Compared to the conventional approach of water replenishment, performance analysis results revealed 44% to 58% water economy when the zeer pot’s water was replenished based on the model’s prediction; while there was no significant difference in the shelf-life of the fruits preserved with both replenishment methods. Application of the developed water replenishment model facilitates optimal water usage in this system, thereby reducing operational cost of zeer pot refrigerator.

  9. Mechanistic Probes of Zeolitic Imidazolate Framework for Photocatalytic Application

    Energy Technology Data Exchange (ETDEWEB)

    Pattengale, Brian [Department; Yang, Sizhuo [Department; Lee, Sungsik [X-ray; Huang, Jier [Department

    2017-11-07

    In this work, we report a zeolitic imidazolate framework (ZIF-67) with remarkable activity for hydrogen evolution reaction (HER) of 40,500 μmol H2/g MOF, which is, to the best of our knowledge, the highest activity achieved by any MOF system. This result necessitated assessment of its atomic-scale mechanistic function for HER using advanced spectroscopy techniques including time-resolved optical (OTA) and in situ X-ray absorption (XAS) spectroscopy. Through the correlation of OTA results with catalytic performance, we demonstrated that the electron transfer (ET) rather than energy transfer (ENT) pathway between photosensitizer and ZIF-67 is the key factor that controls the efficiency of HER activity, as HER activity that undergoes ET pathway is 3 orders of magnitude higher than that of ENT process. Using in situ XAS, we unraveled the spectral features for key intermediate species which are likely responsible for the rate determining process under turn over conditions. This work represents an original approach to study porous ZIF materials at the molecular level using advanced spectroscopic techniques, providing unprecedented insights into the photoactive nature of ZIF frameworks.

  10. Mechanistic Studies in Friction and Wear of Bulk Materials

    Science.gov (United States)

    Sawyer, W. Gregory; Argibay, Nicolas; Burris, David L.; Krick, Brandon A.

    2014-07-01

    From the context of a contemporary understanding of the phenomenological origins of friction and wear of materials, we review insightful contributions from recent experimental investigations of three classes of materials that exhibit uniquely contrasting tribological behaviors: metals, polymers, and ionic solids. We focus on the past decade of research by the community to better understand the correlations between environment parameters, materials properties, and tribological behavior in systems of increasingly greater complexity utilizing novel synthesis and in situ experimental techniques. In addition to such review, and a half-century after seminal publications on the subject, we present recently acquired evidence linking anisotropy in friction response with anisotropy in wear behavior of crystalline ionic solids as a function of crystallographic orientation. Although the tribological behaviors of metals, polymers, and ionic solids differ widely, it is increasingly more evident that the mechanistic origins (such as fatigue, corrosion, abrasion, and adhesion) are essentially the same. However, we hope to present a clear and compelling argument favoring the prominent and irreplaceable role of in situ experimental techniques as a bridge between fundamental atomistic and molecular processes and emergent behaviors governing tribological contacts.

  11. Rapid Discrimination Among Putative Mechanistic Models of Biochemical Systems.

    Science.gov (United States)

    Lomnitz, Jason G; Savageau, Michael A

    2016-08-31

    An overarching goal in molecular biology is to gain an understanding of the mechanistic basis underlying biochemical systems. Success is critical if we are to predict effectively the outcome of drug treatments and the development of abnormal phenotypes. However, data from most experimental studies is typically noisy and sparse. This allows multiple potential mechanisms to account for experimental observations, and often devising experiments to test each is not feasible. Here, we introduce a novel strategy that discriminates among putative models based on their repertoire of qualitatively distinct phenotypes, without relying on knowledge of specific values for rate constants and binding constants. As an illustration, we apply this strategy to two synthetic gene circuits exhibiting anomalous behaviors. Our results show that the conventional models, based on their well-characterized components, cannot account for the experimental observations. We examine a total of 40 alternative hypotheses and show that only 5 have the potential to reproduce the experimental data, and one can do so with biologically relevant parameter values.

  12. A Mechanistic Model of a Passive Autocatalytic Hydrogen Recombiner

    Directory of Open Access Journals (Sweden)

    Rożeń Antoni

    2015-03-01

    Full Text Available : A passive autocatalytic hydrogen recombiner (PAR is a self-starting device, without operator action or external power input, installed in nuclear power plants to remove hydrogen from the containment building of a nuclear reactor. A new mechanistic model of PAR has been presented and validated by experimental data and results of Computational Fluid Dynamics (CFD simulations. The model allows to quickly and accurately predict gas temperature and composition, catalyst temperature and hydrogen recombination rate. It is assumed in the model that an exothermic recombination reaction of hydrogen and oxygen proceeds at the catalyst surface only, while processes of heat and mass transport occur by assisted natural and forced convection in non-isothermal and laminar gas flow conditions in vertical channels between catalyst plates. The model accounts for heat radiation from a hot catalyst surface and has no adjustable parameters. It can be combined with an equation of chimney draft and become a useful engineering tool for selection and optimisation of catalytic recombiner geometry.

  13. Mechanistic modeling of aberrant energy metabolism in human disease

    Directory of Open Access Journals (Sweden)

    Vineet eSangar

    2012-10-01

    Full Text Available Dysfunction in energy metabolism—including in pathways localized to the mitochondria—has been implicated in the pathogenesis of a wide array of disorders, ranging from cancer to neurodegenerative diseases to type II diabetes. The inherent complexities of energy and mitochondrial metabolism present a significant obstacle in the effort to understand the role that these molecular processes play in the development of disease. To help unravel these complexities, systems biology methods have been applied to develop an array of computational metabolic models, ranging from mitochondria-specific processes to genome-scale cellular networks. These constraint-based models can efficiently simulate aspects of normal and aberrant metabolism in various genetic and environmental conditions. Development of these models leverages—and also provides a powerful means to integrate and interpret—information from a wide range of sources including genomics, proteomics, metabolomics, and enzyme kinetics. Here, we review a variety of mechanistic modeling studies that explore metabolic functions, deficiency disorders, and aberrant biochemical pathways in mitochondria and related regions in the cell.

  14. A mechanistic approach to the generation of sorption databases

    International Nuclear Information System (INIS)

    Bradbury, M.H.; Baeyens, B.

    1992-01-01

    Sorption of radionuclides in the near and far fields of an underground nuclear waste repository is one of the most important processes retarding their release to the environment. In the vast majority of cases sorption data have been presented in terms of empirical parameters such as distribution coefficients and isotherm equations. A consequence of this empirical methodology is that the sorption data are only strictly valid under the experimental conditions at which they were measured. Implicit in this approach is the need to generate large amounts of data and fitting parameters necessary for an empirical description of sorption under all realistically conceivable conditions which may arise in space and time along the migration pathway to Man. An alternative approach to the problem is to try to understand, and develop model descriptions of, underlying retention mechanisms and to identify those systems parameters which essentially determine the extent of sorption. The aim of this work is to see to what extent currently existing mechanistic models, together with their associated data, can be applied to predict sorption data from laboratory experiments on natural systems. This paper describes the current status of this work which is very much in an early stage of development. An example is given whereby model predictions are compared with laboratory results for the sorption of Np at trace concentrations under oxidizing conditions on a series of minerals relevant to granite formations. 31 refs., 11 figs., 5 tabs

  15. Mechanistic Features of Nanodiamonds in the Lapping of Magnetic Heads

    Directory of Open Access Journals (Sweden)

    Xionghua Jiang

    2014-01-01

    Full Text Available Nanodiamonds, which are the main components of slurry in the precision lapping process of magnetic heads, play an important role in surface quality. This paper studies the mechanistic features of nanodiamond embedment into a Sn plate in the lapping process. This is the first study to develop mathematical models for nanodiamond embedment. Such models can predict the optimum parameters for particle embedment. From the modeling calculations, the embedded pressure satisfies p0=3/2·W/πa2 and the indentation depth satisfies δ=k1P/HV. Calculation results reveal that the largest embedded pressure is 731.48 GPa and the critical indentation depth δ is 7 nm. Atomic force microscopy (AFM, scanning electron microscopy (SEM, and Auger electron spectroscopy (AES were used to carry out surface quality detection and analysis of the disk head. Both the formation of black spots on the surface and the removal rate have an important correlation with the size of nanodiamonds. The results demonstrate that an improved removal rate (21 nm·min−1 can be obtained with 100 nm diamonds embedded in the plate.

  16. Mechanistic features of nanodiamonds in the lapping of magnetic heads.

    Science.gov (United States)

    Jiang, Xionghua; Chen, Zhenxing; Wolfram, Joy; Yang, Zhizhou

    2014-01-01

    Nanodiamonds, which are the main components of slurry in the precision lapping process of magnetic heads, play an important role in surface quality. This paper studies the mechanistic features of nanodiamond embedment into a Sn plate in the lapping process. This is the first study to develop mathematical models for nanodiamond embedment. Such models can predict the optimum parameters for particle embedment. From the modeling calculations, the embedded pressure satisfies p 0 = (3/2) · (W/πa (2)) and the indentation depth satisfies δ = k1√P/HV. Calculation results reveal that the largest embedded pressure is 731.48 GPa and the critical indentation depth δ is 7 nm. Atomic force microscopy (AFM), scanning electron microscopy (SEM), and Auger electron spectroscopy (AES) were used to carry out surface quality detection and analysis of the disk head. Both the formation of black spots on the surface and the removal rate have an important correlation with the size of nanodiamonds. The results demonstrate that an improved removal rate (21 nm · min(-1)) can be obtained with 100 nm diamonds embedded in the plate.

  17. Enzymatic Halogenation and Dehalogenation Reactions: Pervasive and Mechanistically Diverse.

    Science.gov (United States)

    Agarwal, Vinayak; Miles, Zachary D; Winter, Jaclyn M; Eustáquio, Alessandra S; El Gamal, Abrahim A; Moore, Bradley S

    2017-04-26

    Naturally produced halogenated compounds are ubiquitous across all domains of life where they perform a multitude of biological functions and adopt a diversity of chemical structures. Accordingly, a diverse collection of enzyme catalysts to install and remove halogens from organic scaffolds has evolved in nature. Accounting for the different chemical properties of the four halogen atoms (fluorine, chlorine, bromine, and iodine) and the diversity and chemical reactivity of their organic substrates, enzymes performing biosynthetic and degradative halogenation chemistry utilize numerous mechanistic strategies involving oxidation, reduction, and substitution. Biosynthetic halogenation reactions range from simple aromatic substitutions to stereoselective C-H functionalizations on remote carbon centers and can initiate the formation of simple to complex ring structures. Dehalogenating enzymes, on the other hand, are best known for removing halogen atoms from man-made organohalogens, yet also function naturally, albeit rarely, in metabolic pathways. This review details the scope and mechanism of nature's halogenation and dehalogenation enzymatic strategies, highlights gaps in our understanding, and posits where new advances in the field might arise in the near future.

  18. A mechanistic study of Protein A chromatography resin lifetime.

    Science.gov (United States)

    Jiang, Canping; Liu, Jing; Rubacha, Michael; Shukla, Abhinav A

    2009-07-31

    A mechanistic study into Protein A chromatographic resin lifetime limitations is presented. Binding and mass transport properties of two widely used agarose-based Protein A resins were studied to distinguish between the roles of resin fouling due to product/impurity build-up and ligand degradation as contributory factors towards the decline in binding capacity with use. Cycling studies were conducted with and without product loading on the columns to separate out the influence of resin fouling. Ligand degradation under the mildly alkaline conditions used for column regeneration was determined to be the primary cause for Protein A resin capacity decline with usage. The use of lower concentrations of caustic and the use of stabilizing excipients to protect the Protein A ligand during cleaning and sanitization were found to be useful techniques in maintaining column performance. The results presented in this paper provide a clearer understanding of the causative factors that limit Protein A chromatographic resin lifetime. It is anticipated that these findings will assist in the development of more robust and economical downstream manufacturing processes for monoclonal antibody and Fc fusion protein purification.

  19. Four Mechanistic Models of Peer Influence on Adolescent Cannabis Use.

    Science.gov (United States)

    Caouette, Justin D; Feldstein Ewing, Sarah W

    2017-06-01

    Most adolescents begin exploring cannabis in peer contexts, but the neural mechanisms that underlie peer influence on adolescent cannabis use are still unknown. This theoretical overview elucidates the intersecting roles of neural function and peer factors in cannabis use in adolescents. Novel paradigms using functional magnetic resonance imaging (fMRI) in adolescents have identified distinct neural mechanisms of risk decision-making and incentive processing in peer contexts, centered on reward-motivation and affect regulatory neural networks; these findings inform a theoretical model of peer-driven cannabis use decisions in adolescents. We propose four "mechanistic profiles" of social facilitation of cannabis use in adolescents: (1) peer influence as the primary driver of use; (2) cannabis exploration as the primary driver, which may be enhanced in peer contexts; (3) social anxiety; and (4) negative peer experiences. Identification of "neural targets" involved in motivating cannabis use may inform clinicians about which treatment strategies work best in adolescents with cannabis use problems, and via which social and neurocognitive processes.

  20. Mechanistic approach to the sodium leakage and fire analysis

    International Nuclear Information System (INIS)

    Yamaguchi, Akira; Muramatsu, Toshiharu; Ohira, Hiroaki; Ida, Masao

    1997-04-01

    In December 1995, a thermocouple well was broken and liquid sodium leaked out of the intermediate heat transport system of the prototype fast breeder reactor Monju. In the initiating process of the incident, liquid sodium flowed out through the hollow thermocouple well, nipple and connector. As a result, liquid sodium, following ignition and combustion, was dropping from the connector to colide with the duct and grating placed below. The collision may cause fragmentation and scattering of the sodium droplet that finally was piled up on the floor. This report deals with the development of computer programs for the phenomena based on mechanistics approach. Numerical analyses are also made for fundamental sodium leakage and combustion phenomenon, sodium combustion experiment, and Monju incident condition. The contents of this report is listed below: (1) Analysis of chemical reaction process based on molecular orbital method, (2) Thermalhy draulic analysis of the sodium combustion experiment II performed in 1996 at O-arai Engineering Center, PNC, (3) Thermalhy draulic analysis of room A-446 of Monju reactor when the sodium leakage took place, (4) Direct numerical simulation of sodium droplet, (5) Sodium leakage and scattering analysis using three dimensional particle method, (6) Multi-dimensional combustion analysis and multi-point approximation combustion analysis code. Subsequent to the development work of the programs, they are to be applied to the safety analysis of the Fast Breeder Reactor. (author)

  1. Mechanistic understanding of monosaccharide-air flow battery electrochemistry

    Science.gov (United States)

    Scott, Daniel M.; Tsang, Tsz Ho; Chetty, Leticia; Aloi, Sekotilani; Liaw, Bor Yann

    Recently, an inexpensive monosaccharide-air flow battery configuration has been demonstrated to utilize a strong base and a mediator redox dye to harness electrical power from the partial oxidation of glucose. Here the mechanistic understanding of glucose oxidation in this unique glucose-air power source is further explored by acid-base titration experiments, 13C NMR, and comparison of results from chemically different redox mediators (indigo carmine vs. methyl viologen) and sugars (fructose vs. glucose) via studies using electrochemical techniques. Titration results indicate that gluconic acid is the main product of the cell reaction, as supported by evidence in the 13C NMR spectra. Using indigo carmine as the mediator dye and fructose as the energy source, an abiotic cell configuration generates a power density of 1.66 mW cm -2, which is greater than that produced from glucose under similar conditions (ca. 1.28 mW cm -2). A faster transition from fructose into the ene-diol intermediate than from glucose likely contributed to this difference in power density.

  2. Warming will affect phytoplankton differently: evidence through a mechanistic approach.

    Science.gov (United States)

    Huertas, I Emma; Rouco, Mónica; López-Rodas, Victoria; Costas, Eduardo

    2011-12-07

    Although the consequences of global warming in aquatic ecosystems are only beginning to be revealed, a key to forecasting the impact on aquatic communities is an understanding of individual species' vulnerability to increased temperature. Despite their microscopic size, phytoplankton support about half of the global primary production, drive essential biogeochemical cycles and represent the basis of the aquatic food web. At present, it is known that phytoplankton are important targets and, consequently, harbingers of climate change in aquatic systems. Therefore, investigating the capacity of phytoplankton to adapt to the predicted warming has become a relevant issue. However, considering the polyphyletic complexity of the phytoplankton community, different responses to increased temperature are expected. We experimentally tested the effects of warming on 12 species of phytoplankton isolated from a variety of environments by using a mechanistic approach able to assess evolutionary adaptation (the so-called ratchet technique). We found different degrees of tolerance to temperature rises and an interspecific capacity for genetic adaptation. The thermal resistance level reached by each species is discussed in relation to their respective original habitats. Our study additionally provides evidence on the most resistant phytoplankton groups in a future warming scenario.

  3. Mechanistic understanding of protein-silicone oil interactions.

    Science.gov (United States)

    Li, Jinjiang; Pinnamaneni, Swathi; Quan, Yong; Jaiswal, Archana; Andersson, Fredrik I; Zhang, Xiaochun

    2012-06-01

    To investigate interactions between protein and silicone oil so that we can provide some mechanistic understanding of protein aggregation in silicone oil lubricated syringes and its prevention by formulation additives such as Polysorbate 80 and Poloxamer 188. Interfacial tension values of silicone oil/water interface of abatacept solutions with and without formulation additives were obtained under equilibrium conditions using Attension Theta optical tensiometer. Their adsorption and desorption profiles were measured using Quartz Crystal Microbalancing with Dissipation monitoring (QCM-D). The degree of aggregation of abatacept was assessed based on size exclusion measurement. Adsorption of abatacept at the oil/water interface was shown. Polysorbat 80 was more effective than Poloxamer 188 in preventing abatacept adsorption. Moreover, it was noted that some of the adsorbed abatacept molecules were not desorbed readily upon buffer rinse. Finally, no homogeneous aggregation was observed at room temperature and a slight increase of aggregation was only observed for samples measured at 40°C which can be prevented using Polysorbate 80. Interfacial adsorption of proteins is the key step and maybe responsible for the phenomenon of soluble-protein loss when contacting silicone oil and the irreversible adsorption of protein may be associated with protein denaturation/aggregation.

  4. A brief review of exercise, bipolar disorder and mechanistic pathways

    Directory of Open Access Journals (Sweden)

    Daniel eThomson

    2015-03-01

    Full Text Available Despite evidence that exercise has been found to be effective in the treatment of depression, it is unclear whether these data can be extrapolated to bipolar disorder. Available evidence for bipolar disorder is scant, with no existing randomised controlled trials having tested the impact of exercise on depressive, manic or hypomanic symptomatology. Although exercise is often recommended in bipolar disorder, this is based on extrapolation from the unipolar literature, theory and clinical expertise and not empirical evidence. In addition, there are currently no available empirical data on program variables, with practical implications on frequency, intensity and type of exercise derived from unipolar depression studies. The aim of the current paper is to explore the relationship between exercise and bipolar disorder and potential mechanistic pathways. Given the high rate of medical co-morbidities experienced by people with bipolar disorder, it is possible that exercise is a potentially useful and important intervention with regard to general health benefits; however, further research is required to elucidate the impact of exercise on mood symptomology.

  5. QlikView scripting

    CERN Document Server

    Floyd, Matt

    2013-01-01

    This mini book offers information about QlikView scripting written in an easy-to-understand manner, and covers QlikView scripting from basic to advanced features in a compact format.If you are a basic orintermediate developer with some knowledge of QlikView applications and a basic understanding of QlikView scripting and data extraction and manipulation, this book will be great for you. If you are an advanced user, you can also use this book as a reference guide and teaching aid. If you are a QlikView project team member such as a business user, data/ETL professional, project manager, orsystem

  6. Synchronizing XPath Views

    DEFF Research Database (Denmark)

    Pedersen, Dennis; Pedersen, Torben Bach

    2004-01-01

    . However, the XML data sources are often independent of the data consumers and may change their schemas without notification, invalidating the XML views defined by the data consumers. This requires the view definitions to be updated to reflect the new structure of the data sources, a process termed view......The increasing availability of XML-based data sources, e.g., for publishing data on the WWW, means that more and more applications (data consumers) rely on accessing and using XML data. Typically, the access is achieved by defining views over the XML data, and accessing data through these views...... synchronization. XPath is the most commonly used language for retrieving parts of XML documents, and is thus an important cornerstone for XML view definitions. This paper presents techniques for discovering schema changes in XML data sources and synchronizing XPath-based views to reflect these schema changes...

  7. Multiple-endpoint assay provides a detailed mechanistic view of responses to herbicide exposure in Chlamydomonas reinhardtii

    Energy Technology Data Exchange (ETDEWEB)

    Nestler, Holger [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, 8600 Duebendorf (Switzerland); ETH Zurich, Swiss Federal Institute of Technology, Institute of Biogeochemistry and Pollutant Dynamics, Universitaetstrasse 16, 8092 Zurich (Switzerland); Groh, Ksenia J.; Schoenenberger, Rene; Behra, Renata [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, 8600 Duebendorf (Switzerland); Schirmer, Kristin [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, 8600 Duebendorf (Switzerland); ETH Zurich, Swiss Federal Institute of Technology, Institute of Biogeochemistry and Pollutant Dynamics, Universitaetstrasse 16, 8092 Zurich (Switzerland); EPF Lausanne, School of Architecture, Civil and Environmental Engineering, 1015 Lausanne (Switzerland); Eggen, Rik I.L. [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, 8600 Duebendorf (Switzerland); ETH Zurich, Swiss Federal Institute of Technology, Institute of Biogeochemistry and Pollutant Dynamics, Universitaetstrasse 16, 8092 Zurich (Switzerland); Suter, Marc J.-F., E-mail: suter@eawag.ch [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, 8600 Duebendorf (Switzerland); ETH Zurich, Swiss Federal Institute of Technology, Institute of Biogeochemistry and Pollutant Dynamics, Universitaetstrasse 16, 8092 Zurich (Switzerland)

    2012-04-15

    The release of herbicides into the aquatic environment raises concerns about potential detrimental effects on ecologically important non-target species, such as unicellular algae, necessitating ecotoxicological risk assessment. Algal toxicity tests based on growth, a commonly assessed endpoint, are integrative, and hence do not provide information about underlying toxic mechanisms and effects. This limitation may be overcome by measuring more specific biochemical and physiological endpoints. In the present work, we developed and applied a novel multiple-endpoint assay, and analyzed the effects of the herbicides paraquat, diuron and norflurazon, each representing a specific mechanism of toxic action, on the single celled green alga Chlamydomonas reinhardtii. The endpoints added to assessment of growth were pigment content, maximum and effective photosystem II quantum yield, ATP content, esterase and oxidative activity. All parameters were measured at 2, 6 and 24 h of exposure, except for growth and pigment content, which were determined after 6 and 24 h only. Effective concentrations causing 50% of response (EC50s) and lowest observable effect concentrations (LOECs) were determined for all endpoints and exposure durations where possible. The assay provided a detailed picture of the concentration- and time-dependent development of effects elicited by the analyzed herbicides, thus improving the understanding of the underlying toxic mechanisms. Furthermore, the response patterns were unique to the respective herbicide and reflected the different mechanisms of toxicity. The comparison of the endpoint responses and sensitivities revealed that several physiological and biochemical parameters reacted earlier or stronger to disturbances than growth. Overall, the presented multiple-endpoint assay constitutes a promising basis for investigating stressor and toxicant effects in green algae.

  8. Multiple-endpoint assay provides a detailed mechanistic view of responses to herbicide exposure in Chlamydomonas reinhardtii

    International Nuclear Information System (INIS)

    Nestler, Holger; Groh, Ksenia J.; Schönenberger, René; Behra, Renata; Schirmer, Kristin; Eggen, Rik I.L.; Suter, Marc J.-F.

    2012-01-01

    The release of herbicides into the aquatic environment raises concerns about potential detrimental effects on ecologically important non-target species, such as unicellular algae, necessitating ecotoxicological risk assessment. Algal toxicity tests based on growth, a commonly assessed endpoint, are integrative, and hence do not provide information about underlying toxic mechanisms and effects. This limitation may be overcome by measuring more specific biochemical and physiological endpoints. In the present work, we developed and applied a novel multiple-endpoint assay, and analyzed the effects of the herbicides paraquat, diuron and norflurazon, each representing a specific mechanism of toxic action, on the single celled green alga Chlamydomonas reinhardtii. The endpoints added to assessment of growth were pigment content, maximum and effective photosystem II quantum yield, ATP content, esterase and oxidative activity. All parameters were measured at 2, 6 and 24 h of exposure, except for growth and pigment content, which were determined after 6 and 24 h only. Effective concentrations causing 50% of response (EC50s) and lowest observable effect concentrations (LOECs) were determined for all endpoints and exposure durations where possible. The assay provided a detailed picture of the concentration- and time-dependent development of effects elicited by the analyzed herbicides, thus improving the understanding of the underlying toxic mechanisms. Furthermore, the response patterns were unique to the respective herbicide and reflected the different mechanisms of toxicity. The comparison of the endpoint responses and sensitivities revealed that several physiological and biochemical parameters reacted earlier or stronger to disturbances than growth. Overall, the presented multiple-endpoint assay constitutes a promising basis for investigating stressor and toxicant effects in green algae.

  9. Mechanistic spatio-temporal point process models for marked point processes, with a view to forest stand data

    DEFF Research Database (Denmark)

    Møller, Jesper; Ghorbani, Mohammad; Rubak, Ege Holger

    We show how a spatial point process, where to each point there is associated a random quantitative mark, can be identified with a spatio-temporal point process specified by a conditional intensity function. For instance, the points can be tree locations, the marks can express the size of trees......, and the conditional intensity function can describe the distribution of a tree (i.e., its location and size) conditionally on the larger trees. This enable us to construct parametric statistical models which are easily interpretable and where likelihood-based inference is tractable. In particular, we consider maximum...... likelihood based inference and tests for independence between the points and the marks....

  10. Resveratrol and the mitochondria: From triggering the intrinsic apoptotic pathway to inducing mitochondrial biogenesis, a mechanistic view.

    Science.gov (United States)

    de Oliveira, Marcos Roberto; Nabavi, Seyed Fazel; Manayi, Azadeh; Daglia, Maria; Hajheydari, Zohreh; Nabavi, Seyed Mohammad

    2016-04-01

    Mitochondria, the power plants of the cell, are known as a cross-road of different cellular signaling pathways. These cytoplasmic double-membraned organelles play a pivotal role in energy metabolism and regulate calcium flux in the cells. It is well known that mitochondrial dysfunction is associated with different diseases such as neurodegeneration and cancer. A growing body of literature has shown that polyphenolic compounds exert direct effects on mitochondrial ultra-structure and function. Resveratrol is known as one of the most common bioactive constituents of red wine, which improves mitochondrial functions under in vitro and in vivo conditions. This paper aims to review the molecular pathways underlying the beneficial effects of resveratrol on mitochondrial structure and functions. In addition, we discuss the chemistry and main sources of resveratrol. Resveratrol represents the promising effects on mitochondria in different experimental models. However, there are several reports on the detrimental effects elicited by resveratrol on mitochondria. An understanding of the chemistry and source of resveratrol, its bioavailability and the promising effects on mitochondria brings a new hope to therapy of mitochondrial dysfunction-related diseases. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Mechanistic features of isomerizing alkoxycarbonylation of methyl oleate

    KAUST Repository

    Roesle, Philipp

    2012-10-24

    The weakly coordinated triflate complex [(P̂P)Pd(OTf)] +(OTf)- (1) (P̂P = 1,3-bis(di-tert- butylphosphino)propane) is a suitable reactive precursor for mechanistic studies of the isomerizing alkoxcarbonylation of methyl oleate. Addition of CH 3OH or CD3OD to 1 forms the hydride species [(P ̂P)PdH(CH3OH)]+(OTf)- (2-CH3OH) or the deuteride [(P̂P)PdD(CD 3OD)]+(OTf)- (2D-CD3OD), respectively. Further reaction with pyridine cleanly affords the stable and isolable hydride [(P̂P)PdH(pyridine)]+(OTf) - (2-pyr). This complex yields the hydride fragment free of methanol by abstraction of pyridine with BF3OEt2, and thus provides an entry to mechanistic observations including intermediates reactive toward methanol. Exposure of methyl oleate (100 equiv) to 2D-CD 3OD resulted in rapid isomerization to the thermodynamic isomer distribution, 94.3% of internal olefins, 5.5% of α,β-unsaturated ester and <0.2% of terminal olefin. Reaction of 2-pyr/BF3OEt 2 with a stoichiometric amount of 1-13C-labeled 1-octene at -80 °C yields a 50:50 mixture of the linear alkyls [(P ̂P)Pd13CH2(CH2) 6CH3]+ and [(P̂P)PdCH 2(CH2)6 13CH3] + (4a and 4b). Further reaction with 13CO yields the linear acyls [(P̂P)Pd13C(=O)12/13CH 2(CH2)6 12/13CH3(L)] + (5-L; L = solvent or 13CO). Reaction of 2-pyr/BF 3·OEt2 with a stoichiometric amount of methyl oleate at -80 °C also resulted in fast isomerization to form a linear alkyl species [(P̂P)PdCH2(CH2) 16C(=O)OCH3]+ (6) and a branched alkyl stabilized by coordination of the ester carbonyl group as a four membered chelate [(P̂P)PdCH{(CH2)15CH 3}C(=O)OCH3]+ (7). Addition of carbon monoxide (2.5 equiv) at -80 °C resulted in insertion to form the linear acyl carbonyl [(P̂P)PdC(=O)(CH2)17C(=O)OCH 3(CO)]+ (8-CO) and the five-membered chelate [(P ̂P)PdC(=O)CH{(CH2)15CH3}C(=O) OCH3]+ (9). Exposure of 8-CO and 9 to 13CO at -50 °C results in gradual incorporation of the 13C label. Reversibility of 7 + CO ⇄ 9 is also evidenced by ΔG = -2.9 kcal mol-1 and

  12. The attention schema theory: a mechanistic account of subjective awareness

    Directory of Open Access Journals (Sweden)

    Taylor W. Webb

    2015-04-01

    Full Text Available We recently proposed the attention schema theory, a novel way to explain the brain basis of subjective awareness in a mechanistic and scientifically testable manner. The theory begins with attention, the process by which signals compete for the brain’s limited computing resources. This internal signal competition is partly under a bottom-up influence and partly under top-down control. We propose that the top-down control of attention is improved when the brain has access to a simplified model of attention itself. The brain therefore constructs a schematic model of the process of attention, the ‘attention schema’, in much the same way that it constructs a schematic model of the body, the ‘body schema’. The content of this internal model leads a brain to conclude that it has a subjective experience. One advantage of this theory is that it explains how awareness and attention can sometimes become dissociated; the brain’s internal models are never perfect, and sometimes a model becomes dissociated from the object being modeled. A second advantage of this theory is that it explains how we can be aware of both internal and external events. The brain can apply attention to many types of information including external sensory information and internal information about emotions and cognitive states. If awareness is a model of attention, then this model should pertain to the same domains of information to which attention pertains. A third advantage of this theory is that it provides testable predictions. If awareness is the internal model of attention, used to help control attention, then without awareness, attention should still be possible but should suffer deficits in control. In this article, we review the existing literature on the relationship between attention and awareness, and suggest that at least some of the predictions of the theory are borne out by the evidence.

  13. Radiation induced base excision repair (BER): a mechanistic mathematical approach.

    Science.gov (United States)

    Rahmanian, Shirin; Taleei, Reza; Nikjoo, Hooshang

    2014-10-01

    This paper presents a mechanistic model of base excision repair (BER) pathway for the repair of single-stand breaks (SSBs) and oxidized base lesions produced by ionizing radiation (IR). The model is based on law of mass action kinetics to translate the biochemical processes involved, step-by-step, in the BER pathway to translate into mathematical equations. The BER is divided into two subpathways, short-patch repair (SPR) and long-patch repair (LPR). SPR involves in replacement of single nucleotide via Pol β and ligation of the ends via XRCC1 and Ligase III, while LPR involves in replacement of multiple nucleotides via PCNA, Pol δ/ɛ and FEN 1, and ligation via Ligase I. A hallmark of IR is the production of closely spaced lesions within a turn of DNA helix (named complex lesions), which have been attributed to a slower repair process. The model presented considers fast and slow component of BER kinetics by assigning SPR for simple lesions and LPR for complex lesions. In the absence of in vivo reaction rate constants for the BER proteins, we have deduced a set of rate constants based on different published experimental measurements including accumulation kinetics obtained from UVA irradiation, overall SSB repair kinetic experiments, and overall BER kinetics from live-cell imaging experiments. The model was further used to calculate the repair kinetics of complex base lesions via the LPR subpathway and compared to foci kinetic experiments for cells irradiated with γ rays, Si, and Fe ions. The model calculation show good agreement with experimental measurements for both overall repair and repair of complex lesions. Furthermore, using the model we explored different mechanisms responsible for inhibition of repair when higher LET and HZE particles are used and concluded that increasing the damage complexity can inhibit initiation of LPR after the AP site removal step in BER. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Toward a Mechanistic Modeling of Nitrogen Limitation on Vegetation Dynamics

    Science.gov (United States)

    Xu, Chonggang; Fisher, Rosie; Wullschleger, Stan D.; Wilson, Cathy J.; Cai, Michael; McDowell, Nate G.

    2012-01-01

    Nitrogen is a dominant regulator of vegetation dynamics, net primary production, and terrestrial carbon cycles; however, most ecosystem models use a rather simplistic relationship between leaf nitrogen content and photosynthetic capacity. Such an approach does not consider how patterns of nitrogen allocation may change with differences in light intensity, growing-season temperature and CO2 concentration. To account for this known variability in nitrogen-photosynthesis relationships, we develop a mechanistic nitrogen allocation model based on a trade-off of nitrogen allocated between growth and storage, and an optimization of nitrogen allocated among light capture, electron transport, carboxylation, and respiration. The developed model is able to predict the acclimation of photosynthetic capacity to changes in CO2 concentration, temperature, and radiation when evaluated against published data of Vc,max (maximum carboxylation rate) and Jmax (maximum electron transport rate). A sensitivity analysis of the model for herbaceous plants, deciduous and evergreen trees implies that elevated CO2 concentrations lead to lower allocation of nitrogen to carboxylation but higher allocation to storage. Higher growing-season temperatures cause lower allocation of nitrogen to carboxylation, due to higher nitrogen requirements for light capture pigments and for storage. Lower levels of radiation have a much stronger effect on allocation of nitrogen to carboxylation for herbaceous plants than for trees, resulting from higher nitrogen requirements for light capture for herbaceous plants. As far as we know, this is the first model of complete nitrogen allocation that simultaneously considers nitrogen allocation to light capture, electron transport, carboxylation, respiration and storage, and the responses of each to altered environmental conditions. We expect this model could potentially improve our confidence in simulations of carbon-nitrogen interactions and the vegetation feedbacks

  15. Mechanistic Understanding of Microbial Plugging for Improved Sweep Efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Steven Bryant; Larry Britton

    2008-09-30

    Microbial plugging has been proposed as an effective low cost method of permeability reduction. Yet there is a dearth of information on the fundamental processes of microbial growth in porous media, and there are no suitable data to model the process of microbial plugging as it relates to sweep efficiency. To optimize the field implementation, better mechanistic and volumetric understanding of biofilm growth within a porous medium is needed. In particular, the engineering design hinges upon a quantitative relationship between amount of nutrient consumption, amount of growth, and degree of permeability reduction. In this project experiments were conducted to obtain new data to elucidate this relationship. Experiments in heterogeneous (layered) beadpacks showed that microbes could grow preferentially in the high permeability layer. Ultimately this caused flow to be equally divided between high and low permeability layers, precisely the behavior needed for MEOR. Remarkably, classical models of microbial nutrient uptake in batch experiments do not explain the nutrient consumption by the same microbes in flow experiments. We propose a simple extension of classical kinetics to account for the self-limiting consumption of nutrient observed in our experiments, and we outline a modeling approach based on architecture and behavior of biofilms. Such a model would account for the changing trend of nutrient consumption by bacteria with the increasing biomass and the onset of biofilm formation. However no existing model can explain the microbial preference for growth in high permeability regions, nor is there any obvious extension of the model for this observation. An attractive conjecture is that quorum sensing is involved in the heterogeneous bead packs.

  16. Vitamins C and E: beneficial effects from a mechanistic perspective.

    Science.gov (United States)

    Traber, Maret G; Stevens, Jan F

    2011-09-01

    The mechanistic properties of two dietary antioxidants that are required by humans, vitamins C and E, are discussed relative to their biological effects. Vitamin C (ascorbic acid) is an essential cofactor for α-ketoglutarate-dependent dioxygenases. Examples are prolyl hydroxylases, which play a role in the biosynthesis of collagen and in down-regulation of hypoxia-inducible factor (HIF)-1, a transcription factor that regulates many genes responsible for tumor growth, energy metabolism, and neutrophil function and apoptosis. Vitamin C-dependent inhibition of the HIF pathway may provide alternative or additional approaches for controlling tumor progression, infections, and inflammation. Vitamin E (α-tocopherol) functions as an essential lipid-soluble antioxidant, scavenging hydroperoxyl radicals in a lipid milieu. Human symptoms of vitamin E deficiency suggest that its antioxidant properties play a major role in protecting erythrocyte membranes and nervous tissues. As an antioxidant, vitamin C provides protection against oxidative stress-induced cellular damage by scavenging of reactive oxygen species, by vitamin E-dependent neutralization of lipid hydroperoxyl radicals, and by protecting proteins from alkylation by electrophilic lipid peroxidation products. These bioactivities bear relevance to inflammatory disorders. Vitamin C also plays a role in the function of endothelial nitric oxide synthase (eNOS) by recycling the eNOS cofactor, tetrahydrobiopterin, which is relevant to arterial elasticity and blood pressure regulation. Evidence from plants supports a role for vitamin C in the formation of covalent adducts with electrophilic secondary metabolites. Mechanism-based effects of vitamin C and E supplementation on biomarkers and on clinical outcomes from randomized, placebo-controlled trials are emphasized in this review. Copyright © 2011 Elsevier Inc. All rights reserved.

  17. Labor Inhibits Placental Mechanistic Target of Rapamycin Complex 1 Signaling

    Science.gov (United States)

    LAGER, Susanne; AYE, Irving L.M.H.; GACCIOLI, Francesca; RAMIREZ, Vanessa I.; JANSSON, Thomas; POWELL, Theresa L.

    2014-01-01

    Introduction Labor induces a myriad of changes in placental gene expression. These changes may represent a physiological adaptation inhibiting placental cellular processes associated with a high demand for oxygen and energy (e.g., protein synthesis and active transport) thereby promoting oxygen and glucose transfer to the fetus. We hypothesized that mechanistic target of rapamycin complex 1 (mTORC1) signaling, a positive regulator of trophoblast protein synthesis and amino acid transport, is inhibited by labor. Methods Placental tissue was collected from healthy, term pregnancies (n=15 no-labor; n=12 labor). Activation of Caspase-1, IRS1/Akt, STAT, mTOR, and inflammatory signaling pathways was determined by Western blot. NFκB p65 and PPARγ DNA binding activity was measured in isolated nuclei. Results Labor increased Caspase-1 activation and mTOR complex 2 signaling, as measured by phosphorylation of Akt (S473). However, mTORC1 signaling was inhibited in response to labor as evidenced by decreased phosphorylation of mTOR (S2448) and 4EBP1 (T37/46 and T70). Labor also decreased NFκB and PPARγ DNA binding activity, while having no effect on IRS1 or STAT signaling pathway. Discussion and conclusion Several placental signaling pathways are affected by labor, which has implications for experimental design in studies of placental signaling. Inhibition of placental mTORC1 signaling in response to labor may serve to down-regulate protein synthesis and amino acid transport, processes that account for a large share of placental oxygen and glucose consumption. We speculate that this response preserves glucose and oxygen for transfer to the fetus during the stressful events of labor. PMID:25454472

  18. Mechanistic kinetic models of enzymatic cellulose hydrolysis-A review.

    Science.gov (United States)

    Jeoh, Tina; Cardona, Maria J; Karuna, Nardrapee; Mudinoor, Akshata R; Nill, Jennifer

    2017-07-01

    Bioconversion of lignocellulose forms the basis for renewable, advanced biofuels, and bioproducts. Mechanisms of hydrolysis of cellulose by cellulases have been actively studied for nearly 70 years with significant gains in understanding of the cellulolytic enzymes. Yet, a full mechanistic understanding of the hydrolysis reaction has been elusive. We present a review to highlight new insights gained since the most recent comprehensive review of cellulose hydrolysis kinetic models by Bansal et al. (2009) Biotechnol Adv 27:833-848. Recent models have taken a two-pronged approach to tackle the challenge of modeling the complex heterogeneous reaction-an enzyme-centric modeling approach centered on the molecularity of the cellulase-cellulose interactions to examine rate limiting elementary steps and a substrate-centric modeling approach aimed at capturing the limiting property of the insoluble cellulose substrate. Collectively, modeling results suggest that at the molecular-scale, how rapidly cellulases can bind productively (complexation) and release from cellulose (decomplexation) is limiting, while the overall hydrolysis rate is largely insensitive to the catalytic rate constant. The surface area of the insoluble substrate and the degrees of polymerization of the cellulose molecules in the reaction both limit initial hydrolysis rates only. Neither enzyme-centric models nor substrate-centric models can consistently capture hydrolysis time course at extended reaction times. Thus, questions of the true reaction limiting factors at extended reaction times and the role of complexation and decomplexation in rate limitation remain unresolved. Biotechnol. Bioeng. 2017;114: 1369-1385. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  19. The ecological impacts of nighttime light pollution: a mechanistic appraisal.

    Science.gov (United States)

    Gaston, Kevin J; Bennie, Jonathan; Davies, Thomas W; Hopkins, John

    2013-11-01

    The ecological impacts of nighttime light pollution have been a longstanding source of concern, accentuated by realized and projected growth in electrical lighting. As human communities and lighting technologies develop, artificial light increasingly modifies natural light regimes by encroaching on dark refuges in space, in time, and across wavelengths. A wide variety of ecological implications of artificial light have been identified. However, the primary research to date is largely focused on the disruptive influence of nighttime light on higher vertebrates, and while comprehensive reviews have been compiled along taxonomic lines and within specific research domains, the subject is in need of synthesis within a common mechanistic framework. Here we propose such a framework that focuses on the cross-factoring of the ways in which artificial lighting alters natural light regimes (spatially, temporally, and spectrally), and the ways in which light influences biological systems, particularly the distinction between light as a resource and light as an information source. We review the evidence for each of the combinations of this cross-factoring. As artificial lighting alters natural patterns of light in space, time and across wavelengths, natural patterns of resource use and information flows may be disrupted, with downstream effects to the structure and function of ecosystems. This review highlights: (i) the potential influence of nighttime lighting at all levels of biological organisation (from cell to ecosystem); (ii) the significant impact that even low levels of nighttime light pollution can have; and (iii) the existence of major research gaps, particularly in terms of the impacts of light at population and ecosystem levels, identification of intensity thresholds, and the spatial extent of impacts in the vicinity of artificial lights. © 2013 The Authors. Biological Reviews © 2013 Cambridge Philosophical Society.

  20. A Mechanistic Link from GABA to Cortical Architecture and Perception.

    Science.gov (United States)

    Kolasinski, James; Logan, John P; Hinson, Emily L; Manners, Daniel; Divanbeighi Zand, Amir P; Makin, Tamar R; Emir, Uzay E; Stagg, Charlotte J

    2017-06-05

    Understanding both the organization of the human cortex and its relation to the performance of distinct functions is fundamental in neuroscience. The primary sensory cortices display topographic organization, whereby receptive fields follow a characteristic pattern, from tonotopy to retinotopy to somatotopy [1]. GABAergic signaling is vital to the maintenance of cortical receptive fields [2]; however, it is unclear how this fine-grain inhibition relates to measurable patterns of perception [3, 4]. Based on perceptual changes following perturbation of the GABAergic system, it is conceivable that the resting level of cortical GABAergic tone directly relates to the spatial specificity of activation in response to a given input [5-7]. The specificity of cortical activation can be considered in terms of cortical tuning: greater cortical tuning yields more localized recruitment of cortical territory in response to a given input. We applied a combination of fMRI, MR spectroscopy, and psychophysics to substantiate the link between the cortical neurochemical milieu, the tuning of cortical activity, and variability in perceptual acuity, using human somatosensory cortex as a model. We provide data that explain human perceptual acuity in terms of both the underlying cellular and metabolic processes. Specifically, higher concentrations of sensorimotor GABA are associated with more selective cortical tuning, which in turn is associated with enhanced perception. These results show anatomical and neurochemical specificity and are replicated in an independent cohort. The mechanistic link from neurochemistry to perception provides a vital step in understanding population variability in sensory behavior, informing metabolic therapeutic interventions to restore perceptual abilities clinically. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  1. Use of Fluorinated Functionality in Enzyme Inhibitor Development: Mechanistic and Analytical Advantages.

    Science.gov (United States)

    Berkowitz, David B; Karukurichi, Kannan R; de la Salud-Bea, Roberto; Nelson, David L; McCune, Christopher D

    2008-09-01

    On the one hand, owing to its electronegativity, relatively small size, and notable leaving group ability from anionic intermediates, fluorine offers unique opportunities for mechanism-based enzyme inhibitor design. On the other, the "bio-orthogonal" and NMR-active 19-fluorine nucleus allows the bioorganic chemist to follow the mechanistic fate of fluorinated substrate analogues or inhibitors as they are enzymatically processed. This article takes an overview of the field, highlighting key developments along these lines. It begins by highlighting new screening methodologies for drug discovery that involve appropriate tagging of either substrate or the target protein itself with (19)F-markers, that then report back on turnover and binding, respectively, via an the NMR screen. Taking this one step further, substrate-tagging with fluorine can be done is such a manner as to provide stereochemical information on enzyme mechanism. For example, substitution of one of the terminal hydrogens in phosphoenolpyruvate, provides insight into the, otherwise latent, facial selectivity of C-C bond formation in KDO synthase. Perhaps, most importantly, from the point of view of this discussion, appropriately tailored fluorinated functionality can be used to form to stabilized "transition state analogue" complexes with a target enzymes. Thus, 5-fluorinated pyrimidines, alpha-fluorinated ketones, and 2-fluoro-2-deoxysugars each lead to covalent adduction of catalytic active site residues in thymidylate synthase, serine protease and glycosidase enzymes, respectively. In all such cases, (19)F NMR allows the bioorganic chemist to spectrally follow "transition state analogue" formation. Finally, the use of specific fluorinated functionality to engineer "suicide substrates" is highlighted in a discussion of the development of the alpha-(2'Z-fluoro)vinyl trigger for amino acid decarboxylase inactivation. Here (19)F NMR allows the bioorganic chemist to glean useful partition ratio data

  2. Use of Gene Expression Changes in Blood to Elucidate Mechanistic Indicators of Childhood Asthma (MICA)

    Science.gov (United States)

    Risk assessment increasingly relies more heavily on mode of action, thus the identification of human bioindicators of disease becomes all the more important. Genomic methods represent a tool for both mode of action determination and bioindicator identification. The Mechanistic In...

  3. Mechanistic-empirical design concepts for continuously reinforced concrete pavements in Illinois.

    Science.gov (United States)

    2009-04-01

    The Illinois Department of Transportation (IDOT) currently has an existing jointed plain concrete pavement : (JPCP) design based on mechanistic-empirical (M-E) principles. However, their continuously reinforced concrete : pavement (CRCP) design proce...

  4. INCORPORATION OF MECHANISTIC INFORMATION IN THE ARSENIC PBPK MODEL DEVELOPMENT PROCESS

    Science.gov (United States)

    INCORPORATING MECHANISTIC INSIGHTS IN A PBPK MODEL FOR ARSENICElaina M. Kenyon, Michael F. Hughes, Marina V. Evans, David J. Thomas, U.S. EPA; Miroslav Styblo, University of North Carolina; Michael Easterling, Analytical Sciences, Inc.A physiologically based phar...

  5. Functional Characterization of Nine Norway Spruce TPS Genes and Evolution of Gymnosperm Terpene Synthases of the TPS-d Subfamily1[w

    Science.gov (United States)

    Martin, Diane M.; Fäldt, Jenny; Bohlmann, Jörg

    2004-01-01

    Constitutive and induced terpenoids are important defense compounds for many plants against potential herbivores and pathogens. In Norway spruce (Picea abies L. Karst), treatment with methyl jasmonate induces complex chemical and biochemical terpenoid defense responses associated with traumatic resin duct development in stems and volatile terpenoid emissions in needles. The cloning of (+)-3-carene synthase was the first step in characterizing this system at the molecular genetic level. Here we report the isolation and functional characterization of nine additional terpene synthase (TPS) cDNAs from Norway spruce. These cDNAs encode four monoterpene synthases, myrcene synthase, (−)-limonene synthase, (−)-α/β-pinene synthase, and (−)-linalool synthase; three sesquiterpene synthases, longifolene synthase, E,E-α-farnesene synthase, and E-α-bisabolene synthase; and two diterpene synthases, isopimara-7,15-diene synthase and levopimaradiene/abietadiene synthase, each with a unique product profile. To our knowledge, genes encoding isopimara-7,15-diene synthase and longifolene synthase have not been previously described, and this linalool synthase is the first described from a gymnosperm. These functionally diverse TPS account for much of the structural diversity of constitutive and methyl jasmonate-induced terpenoids in foliage, xylem, bark, and volatile emissions from needles of Norway spruce. Phylogenetic analyses based on the inclusion of these TPS into the TPS-d subfamily revealed that functional specialization of conifer TPS occurred before speciation of Pinaceae. Furthermore, based on TPS enclaves created by distinct branching patterns, the TPS-d subfamily is divided into three groups according to sequence similarities and functional assessment. Similarities of TPS evolution in angiosperms and modeling of TPS protein structures are discussed. PMID:15310829

  6. Antioxidant Activity of the Essential Oil and its Major Terpenes of Satureja macrostema (Moc. and Sessé ex Benth.) Briq.

    Science.gov (United States)

    Torres-Martínez, Rafael; García-Rodríguez, Yolanda Magdalena; Ríos-Chávez, Patricia; Saavedra-Molina, Alfredo; López-Meza, Joel Edmundo; Ochoa-Zarzosa, Alejandra; Garciglia, Rafael Salgado

    2018-01-01

    The aim of this study was to investigate the in vitro antioxidant activity of Satureja macrostema (Moc. and Sessé ex Benth.) Briq. (Lamiaceae) essential oil, a Mexican medicinal plant known as nurite. Fresh aerial parts of S. macrostema plants cultivated in greenhouse for 3 months were subjected to hydrodistillation in a Clevenger apparatus to obtain essential oil. Volatile compounds were identified by gas chromatography (GC) and GC/mass spectrometry. Antioxidant effectiveness of essential oil and its major terpenes of S. macrostema was examined by three different radical scavenging methods: 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), and total antioxidant capacity (TAC). The concentrations tested were 0.001, 0.01, 0.1, and 1 mg/mL. The major volatile compounds were caryophyllene, limonene, linalool, pulegone, menthone, and thymol. S. macrostema essential oil showed the highest free radical scavenging activity with DPPH and ABTS methods (53.10% and 92.12%, respectively) at 1 mg/mL and 98% with TAC method at 0.1 mg/mL. Thymol exerted the highest antioxidant capacity with 0.1 mg/mL, reaching 83.38%, 96.96%, and 98.57% by DPPH, ABTS, and TAC methods. Caryophyllene, limonene, linalool, pulegone, and menthone exhibited an antioxidant capacity essential oil of S. macrostema and thymol showed a free radical scavenging activity close to that of the synthetic butylated hydroxytoluene. The major volatile compounds of essential oil of Satureja macrostema were caryophyllene, limonene, linalool, pulegone, menthone and thymolThe essential oil of S. macrostema showed a high free radical scavengingThymol exerted the highest antioxidant capacity by DPPH, ABTS and TAC methods. Abbreviations used: GC: Gas Chromatography; DPPH: 2,2-diphenyl-1-picrylhydrazyl; ABTS: 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid; TAC: Total antioxidant capacity.

  7. Molecular Cloning, Characterization, and Functional Analysis of Acetyl-CoA C-Acetyltransferase and Mevalonate Kinase Genes Involved in Terpene Trilactone Biosynthesis from Ginkgo biloba

    Directory of Open Access Journals (Sweden)

    Qiangwen Chen

    2017-01-01

    Full Text Available Ginkgolides and bilobalide, collectively termed terpene trilactones (TTLs, are terpenoids that form the main active substance of Ginkgo biloba. Terpenoids in the mevalonate (MVA biosynthetic pathway include acetyl-CoA C-acetyltransferase (AACT and mevalonate kinase (MVK as core enzymes. In this study, two full-length (cDNAs encoding AACT (GbAACT, GenBank Accession No. KX904942 and MVK (GbMVK, GenBank Accession No. KX904944 were cloned from G. biloba. The deduced GbAACT and GbMVK proteins contain 404 and 396 amino acids with the corresponding open-reading frame (ORF sizes of 1215 bp and 1194 bp, respectively. Tissue expression pattern analysis revealed that GbAACT was highly expressed in ginkgo fruits and leaves, and GbMVK was highly expressed in leaves and roots. The functional complementation of GbAACT in AACT-deficient Saccharomyces cerevisiae strain Δerg10 and GbMVK in MVK-deficient strain Δerg12 confirmed that GbAACT mediated the conversion of mevalonate acetyl-CoA to acetoacetyl-CoA and GbMVK mediated the conversion of mevalonate to mevalonate phosphate. This observation indicated that GbAACT and GbMVK are functional genes in the cytosolic mevalonate (MVA biosynthesis pathway. After G. biloba seedlings were treated with methyl jasmonate and salicylic acid, the expression levels of GbAACT and GbMVK increased, and TTL production was enhanced. The cloning, characterization, expression and functional analysis of GbAACT and GbMVK will be helpful to understand more about the role of these two genes involved in TTL biosynthesis.

  8. Molecular Cloning, Characterization, and Functional Analysis of Acetyl-CoA C-Acetyltransferase and Mevalonate Kinase Genes Involved in Terpene Trilactone Biosynthesis from Ginkgo biloba.

    Science.gov (United States)

    Chen, Qiangwen; Yan, Jiaping; Meng, Xiangxiang; Xu, Feng; Zhang, Weiwei; Liao, Yongling; Qu, Jinwang

    2017-01-02

    Ginkgolides and bilobalide, collectively termed terpene trilactones (TTLs), are terpenoids that form the main active substance of Ginkgo biloba . Terpenoids in the mevalonate (MVA) biosynthetic pathway include acetyl-CoA C -acetyltransferase (AACT) and mevalonate kinase (MVK) as core enzymes. In this study, two full-length (cDNAs) encoding AACT ( GbAACT , GenBank Accession No. KX904942) and MVK ( GbMVK , GenBank Accession No. KX904944) were cloned from G. biloba . The deduced GbAACT and GbMVK proteins contain 404 and 396 amino acids with the corresponding open-reading frame (ORF) sizes of 1215 bp and 1194 bp, respectively. Tissue expression pattern analysis revealed that GbAACT was highly expressed in ginkgo fruits and leaves, and GbMVK was highly expressed in leaves and roots. The functional complementation of GbAACT in AACT-deficient Saccharomyces cerevisiae strain Δerg10 and GbMVK in MVK-deficient strain Δerg12 confirmed that GbAACT mediated the conversion of mevalonate acetyl-CoA to acetoacetyl-CoA and GbMVK mediated the conversion of mevalonate to mevalonate phosphate. This observation indicated that GbAACT and GbMVK are functional genes in the cytosolic mevalonate (MVA) biosynthesis pathway. After G. biloba seedlings were treated with methyl jasmonate and salicylic acid, the expression levels of GbAACT and GbMVK increased, and TTL production was enhanced. The cloning, characterization, expression and functional analysis of GbAACT and GbMVK will be helpful to understand more about the role of these two genes involved in TTL biosynthesis.

  9. Ectopic Terpene Synthase Expression Enhances Sesquiterpene Emission in Nicotiana attenuata without Altering Defense or Development of Transgenic Plants or Neighbors1[W

    Science.gov (United States)

    Schuman, Meredith C.; Palmer-Young, Evan C.; Schmidt, Axel; Gershenzon, Jonathan; Baldwin, Ian T.

    2014-01-01

    Sesquiterpenoids, with approximately 5,000 structures, are the most diverse class of plant volatiles with manifold hypothesized functions in defense, stress tolerance, and signaling between and within plants. These hypotheses have often been tested by transforming plants with sesquiterpene synthases expressed behind the constitutively active 35S promoter, which may have physiological costs measured as inhibited growth and reduced reproduction or may require augmentation of substrate pools to achieve enhanced emission, complicating the interpretation of data from affected transgenic lines. Here, we expressed maize (Zea mays) terpene synthase10 (ZmTPS10), which produces (E)-α-bergamotene and (E)-β-farnesene, or a point mutant ZmTPS10M, which produces primarily (E)-β-farnesene, under control of the 35S promoter in the ecological model plant Nicotiana attenuata. Transgenic N. attenuata plants had specifically enhanced emission of target sesquiterpene(s) with no changes detected in their emission of any other volatiles. Treatment with herbivore or jasmonate elicitors induces emission of (E)-α-bergamotene in wild-type plants and also tended to increase emission of (E)-α-bergamotene and (E)-β-farnesene in transgenics. However, transgenics did not differ from the wild type in defense signaling or chemistry and did not alter defense chemistry in neighboring wild-type plants. These data are inconsistent with within-plant and between-plant signaling functions of (E)-β-farnesene and (E)-α-bergamotene in N. attenuata. Ectopic sesquiterpene emission was apparently not costly for transgenics, which were similar to wild-type plants in their growth and reproduction, even when forced to compete for common resources. These transgenics would be well suited for field experiments to investigate indirect ecological effects of sesquiterpenes for a wild plant in its native habitat. PMID:25187528

  10. Improvements In AF Ablation Outcome Will Be Based More On Technological Advancement Versus Mechanistic Understanding.

    Science.gov (United States)

    Jiang Md, Chen-Yang; Jiang Ms, Ru-Hong

    2014-01-01

    Atrial fibrillation (AF) is one of the most common cardiac arrhythmias. Catheter ablation has proven more effective than antiarrhythmic drugs in preventing clinical recurrence of AF, however long-term outcome remains unsatisfactory. Ablation strategies have evolved based on progress in mechanistic understanding, and technologies have advanced continuously. This article reviews current mechanistic concepts and technological advancements in AF treatment, and summarizes their impact on improvement of AF ablation outcome.

  11. Biomarker Discovery and Mechanistic Studies of Prostate Cancer using Targeted Proteomic Approaches

    Science.gov (United States)

    2012-07-01

    density: a means of distinguishing benign prostatic hypertrophy and prostate cancer. J Urol 147: 815-816, 1992. 11. Catalona WJ, Richie JP, deKernion...Mechanistic Studies of Prostate Cancer using Targeted Proteomic Approaches PRINCIPAL INVESTIGATOR: Haining Zhu, Ph.D...Mechanistic Studies of Prostate Cancer using Targeted Proteomic Approaches 5b. GRANT NUMBER W81XWH-08-1-0430 5c. PROGRAM ELEMENT NUMBER 6

  12. Mechanistic, Mutational, and Structural Evaluation of a Taxus Phenylalanine Aminomutase

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Lei; Wanninayake, Udayanga; Strom, Susan; Geiger, James; Walker, Kevin D. (MSU)

    2014-10-02

    The structure of a phenylalanine aminomutase (TcPAM) from Taxus canadensis has been determined at 2.4 {angstrom} resolution. The active site of the TcPAM contains the signature 4-methylidene-1H-imidazol-5(4H)-one prosthesis, observed in all catalysts of the class I lyase-like family. This catalyst isomerizes (S)-{alpha}-phenylalanine to the (R)-{beta}-isomer by exchange of the NH{sub 2}/H pair. The stereochemistry of the TcPAM reaction product is opposite of the (S)-{beta}-tyrosine made by the mechanistically related tyrosine aminomutase (SgTAM) from Streptomyces globisporus. Since TcPAM and SgTAM share similar tertiary- and quaternary-structures and have several highly conserved aliphatic residues positioned analogously in their active sites for substrate recognition, the divergent product stereochemistries of these catalysts likely cannot be explained by differences in active site architecture. The active site of the TcPAM structure also is in complex with (E)-cinnamate; the latter functions as both a substrate and an intermediate. To account for the distinct (3R)-{beta}-amino acid stereochemistry catalyzed by TcPAM, the cinnamate skeleton must rotate the C{sub 1}-C{sub {alpha}} and C{sub ipso}-C{sub {beta}} bonds 180{sup o} in the active site prior to exchange and rebinding of the NH{sub 2}/H pair to the cinnamate, an event that is not required for the corresponding acrylate intermediate in the SgTAM reaction. Moreover, the aromatic ring of the intermediate makes only one direct hydrophobic interaction with Leu-104. A L104A mutant of TcPAM demonstrated an 1.5-fold increase in k{sub cat} and a decrease in K{sub M} values for sterically demanding 3'-methyl-{alpha}-phenylalanine and styryl-{alpha}-alanine substrates, compared to the kinetic parameters for TcPAM. These parameters did not change significantly for the mutant with 4'-methyl-{alpha}-phenylalanine compared to those for TcPAM.

  13. Mechanistic, kinetic, and processing aspects of tungsten chemical mechanical polishing

    Science.gov (United States)

    Stein, David

    This dissertation presents an investigation into tungsten chemical mechanical polishing (CMP). CMP is the industrially predominant unit operation that removes excess tungsten after non-selective chemical vapor deposition (CVD) during sub-micron integrated circuit (IC) manufacture. This work explores the CMP process from process engineering and fundamental mechanistic perspectives. The process engineering study optimized an existing CMP process to address issues of polish pad and wafer carrier life. Polish rates, post-CMP metrology of patterned wafers, electrical test data, and synergy with a thermal endpoint technique were used to determine the optimal process. The oxidation rate of tungsten during CMP is significantly lower than the removal rate under identical conditions. Tungsten polished without inhibition during cathodic potentiostatic control. Hertzian indenter model calculations preclude colloids of the size used in tungsten CMP slurries from indenting the tungsten surface. AFM surface topography maps and TEM images of post-CMP tungsten do not show evidence of plow marks or intergranular fracture. Polish rate is dependent on potassium iodate concentration; process temperature is not. The colloid species significantly affects the polish rate and process temperature. Process temperature is not a predictor of polish rate. A process energy balance indicates that the process temperature is predominantly due to shaft work, and that any heat of reaction evolved during the CMP process is negligible. Friction and adhesion between alumina and tungsten were studied using modified AFM techniques. Friction was constant with potassium iodate concentration, but varied with applied pressure. This corroborates the results from the energy balance. Adhesion between the alumina and the tungsten was proportional to the potassium iodate concentration. A heuristic mechanism, which captures the relationship between polish rate, pressure, velocity, and slurry chemistry, is presented

  14. Empirical versus mechanistic modelling: comparison of an artificial neural network to a mechanistically based model for quantitative structure pharmacokinetic relationships of a homologous series of barbiturates.

    Science.gov (United States)

    Nestorov, I S; Hadjitodorov, S T; Petrov, I; Rowland, M

    1999-01-01

    The aim of the current study was to compare the predictive performance of a mechanistically based model and an empirical artificial neural network (ANN) model to describe the relationship between the tissue-to-unbound plasma concentration ratios (Kpu's) of 14 rat tissues and the lipophilicity (LogP) of a series of nine 5-n-alkyl-5-ethyl barbituric acids. The mechanistic model comprised the water content, binding capacity, number of the binding sites, and binding association constant of each tissue. A backpropagation ANN with 2 hidden layers (33 neurons in the first layer, 9 neurons in the second) was used for the comparison. The network was trained by an algorithm with adaptive momentum and learning rate, programmed using the ANN Toolbox of MATLAB. The predictive performance of both models was evaluated using a leave-one-out procedure and computation of both the mean prediction error (ME, showing the prediction bias) and the mean squared prediction error (MSE, showing the prediction accuracy). The ME of the mechanistic model was 18% (range, 20 to 57%), indicating a tendency for overprediction; the MSE is 32% (range, 6 to 104%). The ANN had almost no bias: the ME was 2% (range, 36 to 64%) and had greater precision than the mechanistic model, MSE 18% (range, 4 to 70%). Generally, neither model appeared to be a significantly better predictor of the Kpu's in the rat.

  15. Drupal 7 Views Cookbook

    CERN Document Server

    Green, J Ayen

    2012-01-01

    This is a cookbook containing plenty of easy-to-follow practical recipes with screenshots that will help you in mastering the Drupal Views module. Drupal 7 Views Cookbook is for developers or technically proficient users who are fairly comfortable with the concepts behind websites and the Drupal environment.

  16. Mastering QlikView

    CERN Document Server

    Redmond, Stephen

    2014-01-01

    If you are a business application developer or a system analyst who has learned QlikView and Qlik Sense and now want to take your learning to a higher level, then this book is for you.It is assumed that you are aware of the fundamentals of QlikView and have working knowledge of development and in-memory analytics.

  17. VMware horizon view essentials

    CERN Document Server

    von Oven, Peter

    2014-01-01

    If you are a desktop administrator or an end user of a computing project team looking to speed up to the latest VMware Horizon View solution, then this book is perfect for you. It is your ideal companion to deploy a solution to centrally manage and virtualize your desktop estate using Horizon View 6.0.

  18. Síntese de esteres terpenóides por via enzimática: influência do tamanho da cadeia alifática do ácido graxo e da estrutura do álcool de terpeno Synthesis of terpen esters by enzymatic route: influence of the fatty acid size chain and alcohol structure

    Directory of Open Access Journals (Sweden)

    Heizir F. CASTRO

    1997-12-01

    Full Text Available A especificidade de uma preparação comercial de lipase imobilizada, com relação a molécula ácida e alcoólica do substrato, foi estudada através da síntese de diversos ésteres de terpenóides. Na série de reações do citronelol e ácidos graxos com diferentes tamanho de cadeia alifática (C2 a C18, altas taxas de esterificação (95 a 98% foram alcançadas para ácidos contendo 4 ou mais carbonos. Numa segunda série de experimentos, diferentes álcoois terpenos foram esterificados com ácido butírico, sendo constatado uma influência marcante da estrutura do álcool de terpeno no desempenho desta preparação enzimática. Graus de esterificação maiores que 95% somente foram obtidos para os álcoois primários como citronelol, geraniol e nerol. Álcoois secundários (mentol e terciários (linalol não foram esterificados, sob as condições testadas.The selectivity of a commercial immobilized lipase preparation was tested in two set of esterification reactions. In the first group, synthesis were carried out with citronellol and different organic acids (C2 to C18. For this case, with the exception of acetic acid, the size of the carbon chain showed no significant alteration in the esterification rates. Acids containing four or more carbons, were considered to be excellent acyl donors, resulting in the esterification rates in the range of 95% to 98%. Alternatively, the esterification reactions were carried out with different terpen alcohols and butyric acid. The alcohol structure showed to have great influence on the performance of this enzyme preparation. Esterification degree over 95% were attained for primary alcohols such as citronellol, geraniol and nerol. Secondary (menthol and tertiary (linallol were not esterified under the tested conditions.

  19. Experimental investigation and mechanistic modelling of dilute bubbly bulk boiling

    International Nuclear Information System (INIS)

    Kutnjak, Josip

    2013-01-01

    During evaporation the geometric shape of the vapour is not described using thermodynamics. In bubbly flows the bubble shape is considered spheric with small diameters and changing into various shapes upon growth. The heat and mass transfer happens at the interfacial area. The forces acting on the bubbles depend on the bubble diameter and shape. In this work the prediction of the bubble diameter and/or bubble number density in bulk boiling was considered outside the vicinity of the heat input area. Thus the boiling effects that happened inside the nearly saturated bulk were under investigation. This situation is relevant for nuclear safety analysis concerning a stagnant coolant in the spent fuel pool. In this research project a new experimental set-up to investigate was built. The experimental set-up consists of an instrumented, partly transparent, high and slender boiling container for visual observation. The direct visual observation of the boiling phenomena is necessary for the identification of basic mechanisms, which should be incorporated in the simulation model. The boiling process has been recorded by means of video images and subsequently was evaluated by digital image processing methods, and by that data concerning the characteristics of the boiling process were generated for the model development and validation. Mechanistic modelling is based on the derivation of relevant mechanisms concluded from observation, which is in line with physical knowledge. In this context two mechanisms were identified; the growth/-shrink mechanism (GSM) of the vapour bubbles and sudden increases of the bubble number density. The GSM was implemented into the CFD-Code ANSYS-CFX using the CFX Expression Language (CEL) by calculation of the internal bubble pressure using the Young-Laplace-Equation. This way a hysteresis is realised as smaller bubbles have an increased internal pressure. The sudden increases of the bubble number density are explainable by liquid super

  20. Integrating Evolutionary Game Theory into Mechanistic Genotype-Phenotype Mapping.

    Science.gov (United States)

    Zhu, Xuli; Jiang, Libo; Ye, Meixia; Sun, Lidan; Gragnoli, Claudia; Wu, Rongling

    2016-05-01

    Natural selection has shaped the evolution of organisms toward optimizing their structural and functional design. However, how this universal principle can enhance genotype-phenotype mapping of quantitative traits has remained unexplored. Here we show that the integration of this principle and functional mapping through evolutionary game theory gains new insight into the genetic architecture of complex traits. By viewing phenotype formation as an evolutionary system, we formulate mathematical equations to model the ecological mechanisms that drive the interaction and coordination of its constituent components toward population dynamics and stability. Functional mapping provides a procedure for estimating the genetic parameters that specify the dynamic relationship of competition and cooperation and predicting how genes mediate the evolution of this relationship during trait formation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. A view on EOS

    Science.gov (United States)

    Lucchitta, Baerbel K.

    1989-11-01

    I am replying to the recent solicitation to provide views on NASA's Earth Observing System (EOS) to an AGU panel (Eos, October 3, p. 886). My view concerns Landsat. A flashy EOS poster, recently distributed, features six images from space; three of these are from the Landsat satellite. Yet no Landsat-type imaging system is contemplated for EOS. Imaging systems such as HIRIS and HRIS (high-resolution imaging spectrometers) do not give the synoptic view of Landsat and are much too elaborate for simple but invaluable observations of many global- scale processes.

  2. Screening of Polish Fir Honeydew Honey Using GC/MS, HPLC-DAD, and Physical-Chemical Parameters: Benzene Derivatives and Terpenes as Chemical Markers.

    Science.gov (United States)

    Kuś, Piotr M; Jerković, Igor; Marijanović, Zvonimir; Tuberoso, Carlo I G

    2017-09-01

    GC/MS of headspace solid phase micro extraction (HS-SPME) and solvent extractives along with targeted HPLC-DAD of Polish fir (Abies alba Mill.) honeydew honey (FHH), were used to determine the chemical profiles and potential markers of botanical origin. Additionally, typical physical-chemical parameters were also assigned. The values determined for FHH were: conductivity (1.2 mS/cm), water content (16.7 g/100 g), pH (4.5), and CIE chromaticity coordinates (L* = 48.4, a* = 20.6, b* = 69.7, C* = 72.9, and h° = 73.5). FHH contained moderate-high total phenolic content (533.2 mg GAE/kg) and antioxidant activity (1.1 mmol TEAC/kg) and (3.2 mmol Fe 2+ /kg) in DPPH and FRAP assays. The chemical profiles were dominated by source plant-originated benzene derivatives: 3,4-dihydroxybenzoic acid (up to 8.7 mg/kg, HPLC/honey solution), methyl syringate (up to 14.5%, GC/solvent extracts) or benzaldehyde (up to 43.7%, GC/headspace). Other markers were terpenes including norisoprenoid (4-hydroxy-3,5,6-trimethyl-4-(3-oxobut-1-enyl)cyclohex-2-en-1-one, up to 20.3%, GC/solvent extracts) and monoterpenes, mainly linalool derivatives (up to 49%, GC/headspace) as well as borneol (up to 5.9%, GC/headspace). The application of various techniques allowed comprehensive characterisation of FHH. 4-Hydroxy-3,5,6-trimethyl-4-(3-oxobut-1-enyl)cyclohex-2-en-1-one, coniferyl alcohol, borneol, and benzaldehyde were first time proposed for FHH screening. Protocatechuic acid may be a potential marker of FFH regardless of the geographical origin. © 2017 Wiley-VHCA AG, Zurich, Switzerland.

  3. "Private Views" Ungaris

    Index Scriptorium Estoniae

    1999-01-01

    9. juulist Dunaujvarosi Kaasaegse Kunsti Instituudis eesti ja briti kunstnike ühisnäitus "Private Views. Ruum taasavastatud eesti ja briti kaasaegses kunstis". Kuraatorid Pam Skelton, Mare Tralla. Osalejad.

  4. "Private Views" Ungaris

    Index Scriptorium Estoniae

    1999-01-01

    9. juulist Dunaujvarosi Kaasaegse Kunsti Instituudis eesti ja briti kunstnike ühisnäitus "Private Views. Ruum taasavastatud eesti ja briti kaasaegses kunstis" Kuraatorid Pam Skelton, Mare Tralla. Osalejad

  5. Japanese views on ASSET

    International Nuclear Information System (INIS)

    Hirano, M.

    1997-01-01

    The presentation briefly reviews the following aspects directed to ensuring NPP safety: Japanese participation in ASSET activities; views to ASSET activities; recent operating experience in Japan; future ASSET activities

  6. A preliminary study of mechanistic approach in pavement design to accommodate climate change effects

    Science.gov (United States)

    Harnaeni, S. R.; Pramesti, F. P.; Budiarto, A.; Setyawan, A.

    2018-03-01

    Road damage is caused by some factors, including climate changes, overload, and inappropriate procedure for material and development process. Meanwhile, climate change is a phenomenon which cannot be avoided. The effects observed include air temperature rise, sea level rise, rainfall changes, and the intensity of extreme weather phenomena. Previous studies had shown the impacts of climate changes on road damage. Therefore, several measures to anticipate the damage should be considered during the planning and construction in order to reduce the cost of road maintenance. There are three approaches generally applied in the design of flexible pavement thickness, namely mechanistic approach, mechanistic-empirical (ME) approach and empirical approach. The advantages of applying mechanistic approach or mechanistic-empirical (ME) approaches are its efficiency and reliability in the design of flexible pavement thickness as well as its capacity to accommodate climate changes in compared to empirical approach. However, generally, the design of flexible pavement thickness in Indonesia still applies empirical approach. This preliminary study aimed to emphasize the importance of the shifting towards a mechanistic approach in the design of flexible pavement thickness.

  7. Direct analysis of 18 flavonol glycosides, aglycones and terpene trilactones in Ginkgo biloba tablets by matrix solid phase dispersion coupled with ultra-high performance liquid chromatography tandem triple quadrupole mass spectrometry.

    Science.gov (United States)

    Liu, Xin-Guang; Yang, Hua; Cheng, Xiao-Lan; Liu, Lei; Qin, Yong; Wang, Qi; Qi, Lian-Wen; Li, Ping

    2014-08-01

    Analysis and quality control of Ginkgo biloba have been comprehensively studied. However, little attention has been devoted to the simultaneous extraction and analysis of flavonols and terpene trilactones, especially for direct quantification of flavonol glycosides. This work described a rapid strategy for one-step extraction and quantification of the components. A matrix solid phase dispersion (MSPD) method was designed for the extraction of ginkgo ingredients and compared with the heat-reflux and ultrasonic extraction methods. An ultra-high performance liquid chromatography (UHPLC)-tandem-triple-quadrupole-mass spectrometry (QQQ-MS) method was developed for detection of the 18 components, including 10 original flavonol glycosides, 3 aglycones, and 5 lactones. Subsequently, the proposed strategy was used for the analysis of 12 G. biloba tablets. Results showed that MSPD produced comparable extraction efficiency but consumed less time and required lower solvent volumes compared with conventional methods. Without hydrolysis, the concentration detected was much closer to the original in the sample. The total flavonol glycoside contents in ginkgo tablets ranged from 3.59 to 125.21μgmg(-1), and the terpene trilactone varied from 3.45 to 57.8μgmg(-1) among different manufacturers. In conclusion, the proposed MSPD and UHPLC-QQQ-MS is rapid and sensitive in providing comprehensive profile of chemical constituents especially the genuine flavonol glycosides for improved quality control of ginkgo products. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Phytotherapy in diabetes: Review on potential mechanistic perspectives

    Science.gov (United States)

    El-Abhar, Hanan S; Schaalan, Mona F

    2014-01-01

    Diabetes mellitus (DM) is a widely spread epidemic disease that results from the absence of insulin, decreased secretion and/or impaired function. Since DM is a multi-factorial disease, the available pharmaceuticals, despite their sensible treatment, target mostly one pathway to control hyperglycemia and encounter several side effects. Therefore, new therapeutic paradigms aim to hit several pathways using only one agent. Traditionally, antidiabetic plants and/or their active constituents may fulfill this need. More than 200 species of plants possess antidiabetic properties which were evaluated mostly by screening tests without digging far for the exact mode of action. Searching among the different literature resources and various database and in view of the above aspects, the present article provides a comprehensive review on the available antidiabetic plants that have been approved by pharmacological and clinical evaluations, and which their mechanism(s) of action is assured. These plants are categorized according to their proved mode of action and are classified into those that act by inhibiting glucose absorption from intestine, increasing insulin secretion from the pancreas, inhibiting glucose production from hepatocytes, or enhancing glucose uptake by adipose and muscle tissues. The current review also highlights those that mimic in their action the new peptide analogs, such as exenatide, liraglutide and dipeptidylpeptidase-4 inhibitors that increase glucagon-like peptide-1 serum concentration and slow down the gastric emptying. PMID:24748931

  9. Mechanistic investigations of novel photoinitiators for radical polymerization

    International Nuclear Information System (INIS)

    Griesser, M.

    2012-01-01

    Nowadays, there is a wide variety of photoinitiators (PIs) available for radical polymerizations. A common example are two-component (Type II) systems such as benzophenone and tertiary amines. However these systems also suffer from problems due to bimolecularity. These include the possible back electron transfer (BET) leading to deactivation, as well as the solvent cage effect, occurring in highly viscous media. The aim of this thesis was to investigate the reaction mechanism of several photoinitiating systems, which show superior performance. Moreover, they exhibit additional benefits such as circumvention of oxygen inhibition by decarboxylation. Thereby this work helps to understand the molecular basis of the performance of different PI systems. In vestigated PIs included benzaldoxime esters, covalently linked benzophenone and N-phenylglycine as well as derivatives of both systems. Furthermore a PI based on benzophenone extended by ethynyl moeities is discussed. The main tool in this investigation was photo-CIDNP (chemically induced dynamic nuclear polarization), an NMR based technique for studying radical reactions. A complementary view was obtained with TR-EPR (time-resolved electron paramagnetic resonance), which provides direct information about the active radical species. The results were further compared with quantum mechanical calculations (DFT) of the magnetic properties of the radicals. The theoretical approach was further applied to other paramagnetic species such as donor-acceptor systems. (author) [de

  10. A mechanistic analysis of density dependence in algal population dynamics

    Directory of Open Access Journals (Sweden)

    Adrian eBorlestean

    2015-04-01

    Full Text Available Population density regulation is a fundamental principle in ecology, but the specific process underlying functional expression of density dependence remains to be fully elucidated. One view contends that patterns of density dependence are largely fixed across a species irrespective of environmental conditions, whereas another is that the strength and expression of density dependence are fundamentally variable depending on the nature of exogenous or endogenous constraints acting on the population. We conducted a study investigating the expression of density dependence in Chlamydomonas spp. grown under a gradient from low to high nutrient density. We predicted that the relationship between per capita growth rate (pgr and population density would vary from concave up to concave down as nutrient density became less limiting and populations experienced weaker density regulation. Contrary to prediction, we found that the relationship between pgr and density became increasingly concave-up as nutrient levels increased. We also found that variation in pgr increased, and pgr levels reached higher maxima in nutrient-limited environments. Most likely, these results are attributable to population growth suppression in environments with high intraspecific competition due to limited nutrient resources. Our results suggest that density regulation is strongly variable depending on exogenous and endogenous processes acting on the population, implying that expression of density dependence depends extensively on local conditions. Additional experimental work should reveal the mechanisms influencing how the expression of density dependence varies across populations through space and time.

  11. Integrating mechanistic organism--environment interactions into the basic theory of community and evolutionary ecology.

    Science.gov (United States)

    Baskett, Marissa L

    2012-03-15

    This paper presents an overview of how mechanistic knowledge of organism-environment interactions, including biomechanical interactions of heat, mass and momentum transfer, can be integrated into basic theoretical population biology through mechanistic functional responses that quantitatively describe how organisms respond to their physical environment. Integrating such functional responses into simple community and microevolutionary models allows scaling up of the organism-level understanding from biomechanics both ecologically and temporally. For community models, Holling-type functional responses for predator-prey interactions provide a classic example of the functional response affecting qualitative model dynamics, and recent efforts are expanding analogous models to incorporate environmental influences such as temperature. For evolutionary models, mechanistic functional responses dependent on the environment can serve as fitness functions in both quantitative genetic and game theoretic frameworks, especially those concerning function-valued traits. I present a novel comparison of a mechanistic fitness function based on thermal performance curves to a commonly used generic fitness function, which quantitatively differ in their predictions for response to environmental change. A variety of examples illustrate how mechanistic functional responses enhance model connections to biologically relevant traits and processes as well as environmental conditions and therefore have the potential to link theoretical and empirical studies. Sensitivity analysis of such models can provide biologically relevant insight into which parameters and processes are important to community and evolutionary responses to environmental change such as climate change, which can inform conservation management aimed at protecting response capacity. Overall, the distillation of detailed knowledge or organism-environment interactions into mechanistic functional responses in simple population

  12. Immersive viewing engine

    Science.gov (United States)

    Schonlau, William J.

    2006-05-01

    An immersive viewing engine providing basic telepresence functionality for a variety of application types is presented. Augmented reality, teleoperation and virtual reality applications all benefit from the use of head mounted display devices that present imagery appropriate to the user's head orientation at full frame rates. Our primary application is the viewing of remote environments, as with a camera equipped teleoperated vehicle. The conventional approach where imagery from a narrow field camera onboard the vehicle is presented to the user on a small rectangular screen is contrasted with an immersive viewing system where a cylindrical or spherical format image is received from a panoramic camera on the vehicle, resampled in response to sensed user head orientation and presented via wide field eyewear display, approaching 180 degrees of horizontal field. Of primary interest is the user's enhanced ability to perceive and understand image content, even when image resolution parameters are poor, due to the innate visual integration and 3-D model generation capabilities of the human visual system. A mathematical model for tracking user head position and resampling the panoramic image to attain distortion free viewing of the region appropriate to the user's current head pose is presented and consideration is given to providing the user with stereo viewing generated from depth map information derived using stereo from motion algorithms.

  13. The overrated role of 'promotion' in mechanistic modelling of radiation carcinogenesis

    International Nuclear Information System (INIS)

    Brugmans, Marco J.P.; Bijwaard, Harmen; Leenhouts, Henk P.

    2002-01-01

    It is argued that the 'cellular' dose-response relationships of model parameters cannot be determined from mechanistic model fits to experimental or epidemiologic cancer data. Baseline population cancer incidence data show conclusions about intermediate cell kinetics to be especially questionable. Here we recommend that mechanistic models should be applied solely in one direction: by starting from known cellular dose-response relationships the models aim at providing a biologically motivated consistent description of the development of radiation-induced cancer for different exposures, which is very important for low-dose risk estimation. (author)

  14. Mechanistic Models for Process Development and Optimization of Fed-batch Fermentation Systems

    DEFF Research Database (Denmark)

    Mears, Lisa; Stocks, Stuart M.; Albæk, Mads O.

    2016-01-01

    . This is based on on-line gas measurements and ammonia addition flow rate measurements. Additionally, a mechanistic model is applied offline as a tool for batch planning, based on definition of the process back pressure, aeration rate and stirrer speed. This allows the batch starting fill to be planned, taking...... into account the oxygen transfer conditions, as well as the evaporation rates of the system. Mechanistic models are valuable tools which are applicable for both process development and optimization. The state estimator described will be a valuable tool for future work as part of control strategy development...... for on-line process control and optimization....

  15. Nursing student-patient relationships: a descriptive study of students' and patients' views.

    Science.gov (United States)

    Suikkala, Arja; Leino-Kilpi, Helena; Katajisto, Jouko

    2008-01-01

    This study was designed to describe and compare nursing students' and patients' perceptions of the relationship between students and patients. The data was collected in Finland from a convenience sample of nursing students (n=290) and patients (n=242) using questionnaires especially designed for this study. The results indicated that students viewed the relationship as more authoritative and facilitative, while patients regarded the relationship as more mechanistic. Furthermore, students' and patients' views on their relationships differed significantly. These results have important implications for nursing education. They particularly highlight the need to further strengthen nursing student-patient interactions and relationships.

  16. Remote viewing of objects

    International Nuclear Information System (INIS)

    Motin, J.D.; Reformatsky, I.A.; Sinitsyn, P.R.; Ivanov, N.M.; Ivanov, B.I.; Malakhov, I.K.

    1979-01-01

    An object in a nuclear power plant is viewed through a radiation-proof shield by means of an entrance lens, optic fibre bundle and exit lens. The optic fibre bundle being heated to ensure thermostabilization of its light conducting properties in the presence of ionising radiation. Heating is by an electric heating coil. Alternatively, heating may be by argon itself heated by an electric heating element, a coating of resistive heating material, or absorption of neutrons in the material of the fibres or a coating therefor. Viewing may be on a CRT screen. (author)

  17. Clashing world views

    International Nuclear Information System (INIS)

    Lagassa, G.

    1992-01-01

    This article examines how politics, economics, and an increasing awareness of environmental and societal impacts are affecting the market for new hydroelectric projects. The topics of the article include border conflicts, new opposition, resettlement issues, the problems and benefits of hydroelectric projects, taking action, and a clash of world views

  18. Summary: Two Views.

    Science.gov (United States)

    Sharp, W. Harry; Hurst, James C.

    1979-01-01

    Two student services administrators present differing views on the role of consultation in the university community. These authors, speaking from one of the most inclusive levels of the university system, raise a number of issues concerning the pros and cons of intersystem consultation within the university. (Author)

  19. to view fulltext PDF

    Indian Academy of Sciences (India)

    2012-01-08

    Jan 8, 2012 ... Herein, we review recent findings supporting the view that autophagy, one of the major protein degradation systems, is critically involved in Aβ homeostasis and AD pathogenesis, and discuss possible therapeutic strategies targeting autophagic activity in alleviating the Aβ-associated pathogenesis of AD.

  20. VMware view security essentials

    CERN Document Server

    Langenhan, Daniel

    2013-01-01

    A practical and fast-paced guide that gives you all the information you need to secure your virtual environment.This book is a ""how-to"" for the novice, a ""reference guide"" for the advanced user, and a ""go to"" for the experienced user in all the aspects of VMware View desktop virtualization security.

  1. to view fulltext PDF

    Indian Academy of Sciences (India)

    Abstract. In the rapidly developing field of study of the transient sky, fast radio transients are perhaps the most exciting objects of scrutiny at present. The SKA, with its wide field-of-view and significant improve- ment in sensitivity over existing facilities, is expected to detect a plethora of fast transients which, in addition to help ...

  2. Post-human Viewing

    DEFF Research Database (Denmark)

    Blaagaard, Bolette

    2013-01-01

    This article discusses the relationship between theories of photography and mobile phone footage. In doing so, it asks if theories of photography still apply in a technologically saturated world of imagery. Technology is an increasingly important part of viewing imagery today and enables imagery...

  3. to view fulltext PDF

    Indian Academy of Sciences (India)

    IAS Admin

    cause it corresponds to what our eye or an optical instru- ment sees as brightness. You can develop an intuitive feel for the invariance of surface brightness by carry- ing out the following experiment. Stand at a distance of about a metre from a plain white wall and view it through a cone made of a rolled-up piece of paper, ...

  4. to view fulltext PDF

    Indian Academy of Sciences (India)

    Nevertheless, P1 peptidase in many ways is still a mysterious viral protein. In this review, we would like to offer a comprehensive overview, discussing the proteomic, biochemical and phylogenetic views of the P1 protein. 1. Introduction. The Potyviridae family [named after its type member,. Potato virus Y (PVY)] is the largest ...

  5. Lipids, adiposity and tendinopathy : is there a mechanistic link? Critical review

    NARCIS (Netherlands)

    Scott, Alex; Zwerver, Johannes; Grewal, Navi; de Sa, Agnetha; Alktebi, Thuraya; Granville, David J.; Hart, David A.

    Being overweight or obese is associated with an elevated risk of tendon pathology. However, for sportspeople the epidemiological data linking weight or adiposity on one hand, and risk of tendon pathology on the other, are less consistent. Indeed, the mechanistic links between diet, adiposity and

  6. Mechanistic aspects of Os(VIII) catalysed oxidation of loop diuretic ...

    Indian Academy of Sciences (India)

    Mechanistic aspects of Os(VIII) catalysed oxidation of loop diuretic drug furosemide by Ag(III) periodate complex in aqueous alkaline medium. SHWETA J MALODEa, NAGARAJ P SHETTIb and SHARANAPPA T NANDIBEWOORa,∗. aPost-Graduate Department of Studies in Chemistry, Karnatak University, Dharwad 580 ...

  7. Mechanistic modelling of weak interlayers in flexible and semi-flexible road pavements: Part 2

    CSIR Research Space (South Africa)

    De Beer, Morris

    2012-04-01

    Full Text Available and investigate the existence of these weak layers in cemented pavement layers. In Part 2, several cases of the above conditions for different road pavement types are discussed, with field examples. Mechanistic analyses were done on a typical hot mix asphalt (HMA...

  8. Mechanistic and kinetic aspects of pentose dehydration towards furfural in aqueous media employing homogeneous catalysis

    NARCIS (Netherlands)

    Danon, B.; Marcotullio, G.; De Jong, W.

    2013-01-01

    In this paper both the mechanistic and kinetic aspects of furfural formation from pentoses in aqueous acidic media have been reviewed. Based on the reviewed literature, a comprehensive reaction mechanism has been proposed consisting of more than one route, all starting from acyclic xylose, and

  9. Atomization of bismuthane in a dielectric barrier discharge: A mechanistic study

    Czech Academy of Sciences Publication Activity Database

    Kratzer, Jan; Zelina, Ondřej; Svoboda, Milan; Sturgeon, R. E.; Mester, Z.; Dědina, Jiří

    2016-01-01

    Roč. 88, č. 3 (2016), s. 1804-1811 ISSN 0003-2700 R&D Projects: GA ČR GA14-23532S Grant - others:GA AV ČR(CZ) M200311202 Institutional support: RVO:68081715 Keywords : dielectric barrier discharge * hydride generation * mechanistic study Subject RIV: CB - Analytical Chemistry , Separation Impact factor: 6.320, year: 2016

  10. Combining correlative and mechanistic habitat suitability models to improve ecological compensation.

    Science.gov (United States)

    Meineri, Eric; Deville, Anne-Sophie; Grémillet, David; Gauthier-Clerc, Michel; Béchet, Arnaud

    2015-02-01

    Only a few studies have shown positive impacts of ecological compensation on species dynamics affected by human activities. We argue that this is due to inappropriate methods used to forecast required compensation in environmental impact assessments. These assessments are mostly descriptive and only valid at limited spatial and temporal scales. However, habitat suitability models developed to predict the impacts of environmental changes on potential species' distributions should provide rigorous science-based tools for compensation planning. Here we describe the two main classes of predictive models: correlative models and individual-based mechanistic models. We show how these models can be used alone or synoptically to improve compensation planning. While correlative models are easier to implement, they tend to ignore underlying ecological processes and lack accuracy. On the contrary, individual-based mechanistic models can integrate biological interactions, dispersal ability and adaptation. Moreover, among mechanistic models, those considering animal energy balance are particularly efficient at predicting the impact of foraging habitat loss. However, mechanistic models require more field data compared to correlative models. Hence we present two approaches which combine both methods for compensation planning, especially in relation to the spatial scale considered. We show how the availability of biological databases and software enabling fast and accurate population projections could be advantageously used to assess ecological compensation requirement efficiently in environmental impact assessments. © 2014 The Authors. Biological Reviews © 2014 Cambridge Philosophical Society.

  11. Students' Interpretations of Mechanistic Language in Organic Chemistry before Learning Reactions

    Science.gov (United States)

    Galloway, Kelli R.; Stoyanovich, Carlee; Flynn, Alison B.

    2017-01-01

    Research on mechanistic thinking in organic chemistry has shown that students attribute little meaning to the electron-pushing (i.e., curved arrow) formalism. At the University of Ottawa, a new curriculum has been developed in which students are taught the electron-pushing formalism prior to instruction on specific reactions--this formalism is…

  12. Atomization of bismuthane in a dielectric barrier discharge: A mechanistic study

    Czech Academy of Sciences Publication Activity Database

    Kratzer, Jan; Zelina, Ondřej; Svoboda, Milan; Sturgeon, R. E.; Mester, Z.; Dědina, Jiří

    2016-01-01

    Roč. 88, č. 3 (2016), s. 1804-1811 ISSN 0003-2700 R&D Projects: GA ČR GA14-23532S Grant - others:GA AV ČR(CZ) M200311202 Institutional support: RVO:68081715 Keywords : dielectric barrier discharge * hydride generation * mechanistic study Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 6.320, year: 2016

  13. Mechanistic aspects of ligand substitution on [(H 2 O)(tap) 2 RuORu ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 124; Issue 3. Mechanistic aspects of ligand substitution on [(H2O)(tap)2RuORu(tap)2(H2O)]2+ {tap=2-(m-tolylazo)pyridine} ion by three glycine-containing dipeptides in aqueous medium at physiological pH. Arup Mandal Subala Mondal Parnajyoti Karmakar Biplab K ...

  14. A dynamic mechanistic model of lactic acid metabolism in the rumen

    NARCIS (Netherlands)

    Mills, J.A.N.; Crompton, L.A.; Ellis, J.L.; Dijkstra, J.; Bannink, A.; Hook, S.E.; Benchaar, C.; France, J.

    2014-01-01

    Current feed evaluation systems for ruminants are too imprecise to describe diets in terms of their acidosis risk. The dynamic mechanistic model described herein arises from the integration of a lactic acid (La) metabolism module into an extant model of whole-rumen function. The model was evaluated

  15. Predictive mechanistic bioenergetics to model habitat suitability of shellfish culture in coastal lakes

    Science.gov (United States)

    Rinaldi, A.; Montalto, V.; Manganaro, A.; Mazzola, A.; Mirto, S.; Sanfilippo, M.; Sarà, G.

    2014-05-01

    Quantitative tools based on mechanistic modelling of functional traits able to enhance the sustainability of aquaculture and most other human activities (i.e. reducing the likelihood of detrimental impacts optimising productions), are especially important factors in the decision to site aquaculture facilities in coastal lakes, ponds and lagoons and, in the case of detrimental impact, to adopt mitigation measures. We tested the ability of mechanistic functional trait based models to predict life history traits of cultivable shellfish in shallow coastal lakes. Dynamic Energy Budget (DEB) models were run to generate spatially explicit predictions of Mytilus galloprovincialis life history (LH) traits (e.g. body size and fecundity). Using fortnightly data of food supply and hourly data of body temperatures, and exploiting the power of mechanistic rules, we estimated the amount of faeces ejected by a fixed quantity of organisms cultivated in two shallow Southern Mediterranean (Sicily) lakes. These differed in terms of temperature and food density, implying large differences in life history traits of mussels in the two study areas. This information could help facilitate the selection of sites where environmental conditions are more suitable for aquaculture and contextually compatible with sustainability. The validation exercise obtained by comparing the predicted and observed data was nearly consistent. Therefore, a mechanistic functional traits-based model seems able to capture the link between habitat characteristics and functional traits of organisms, delineating the fundamental portion of an ecological niche, the possibility of predicting LH traits and potential ecological applications in the management of natural coastal resources.

  16. A Mechanistic Study of Arsenic (III) Rejection by Reverse Osmosis and Nanofiltration Membranes

    Science.gov (United States)

    Suzuki, Tasuma

    2009-01-01

    Reverse osmosis/nanofiltration (RO/NF) membranes are capable to provide an effective barrier for a wide range of contaminants (including disinfection by-products precursors) in a single treatment step. However, solute rejection mechanisms by RO/NF membranes are not well understood. The lack of mechanistic information arises from experimental…

  17. Mechanistic assessment of hillslope transpiration controls of diel subsurface flow: a steady-state irrigation approach

    Science.gov (United States)

    H.R. Barnard; C.B. Graham; W.J. van Verseveld; J.R. Brooks; B.J. Bond; J.J. McDonnell

    2010-01-01

    Mechanistic assessment of how transpiration influences subsurface flow is necessary to advance understanding of catchment hydrology. We conducted a 24-day, steady-state irrigation experiment to quantify the relationships among soil moisture, transpiration and hillslope subsurface flow. Our objectives were to: (1) examine the time lag between maximum transpiration and...

  18. A MECHANISTIC STUDY OF RHODIUM TRI(ORTHO-TERT-BUTYLPHENYL)PHOSPHITE COMPLEXES AS HYDROFORMYLATION CATALYSTS

    NARCIS (Netherlands)

    JONGSMA, T; CHALLA, G; VANLEEUWEN, PWNM

    1991-01-01

    A mechanistic study of the hydroformylation cycle with a rhodium tri(o-t-butylphenyl)phosphite complex as catalyst is presented. Spectroscopic experiments prove that under hydroformylation conditions this complex is coordinated by only one phosphite. The complex has a high activity in the

  19. Mechanistic modeling of pesticide exposure: The missing keystone of honey bee toxicology.

    Science.gov (United States)

    Sponsler, Douglas B; Johnson, Reed M

    2017-04-01

    The role of pesticides in recent honey bee losses is controversial, partly because field studies often fail to detect effects predicted by laboratory studies. This dissonance highlights a critical gap in the field of honey bee toxicology: there exists little mechanistic understanding of the patterns and processes of exposure that link honey bees to pesticides in their environment. The authors submit that 2 key processes underlie honey bee pesticide exposure: 1) the acquisition of pesticide by foraging bees, and 2) the in-hive distribution of pesticide returned by foragers. The acquisition of pesticide by foraging bees must be understood as the spatiotemporal intersection between environmental contamination and honey bee foraging activity. This implies that exposure is distributional, not discrete, and that a subset of foragers may acquire harmful doses of pesticide while the mean colony exposure would appear safe. The in-hive distribution of pesticide is a complex process driven principally by food transfer interactions between colony members, and this process differs importantly between pollen and nectar. High priority should be placed on applying the extensive literature on honey bee biology to the development of more rigorously mechanistic models of honey bee pesticide exposure. In combination with mechanistic effects modeling, mechanistic exposure modeling has the potential to integrate the field of honey bee toxicology, advancing both risk assessment and basic research. Environ Toxicol Chem 2017;36:871-881. © 2016 SETAC. © 2016 SETAC.

  20. Revision of the South African flexible pavement design method; mechanistic-empirical components

    CSIR Research Space (South Africa)

    Theyse, HL

    2007-09-01

    Full Text Available The current version of the South African Mechanistic –Empirical Design Method for flexible pavements is based on technology and models developed during the 1970’s and 1980’s. Given the current level of concern regarding the validity of the results...

  1. A mechanistic modelling and data assimilation approach to estimate the carbon/chlorophyll and carbon/nitrogen ratios in a coupled hydrodynamical-biological model

    Directory of Open Access Journals (Sweden)

    B. Faugeras

    2004-01-01

    Full Text Available The principal objective of hydrodynamical-biological models is to provide estimates of the main carbon fluxes such as total and export oceanic production. These models are nitrogen based, that is to say that the variables are expressed in terms of their nitrogen content. Moreover models are calibrated using chlorophyll data sets. Therefore carbon to chlorophyll (C:Chl and carbon to nitrogen (C:N ratios have to be assumed. This paper addresses the problem of the representation of these ratios. In a 1D framework at the DYFAMED station (NW Mediterranean Sea we propose a model which enables the estimation of the basic biogeochemical fluxes and in which the spatio-temporal variability of the C:Chl and C:N ratios is fully represented in a mechanical way. This is achieved through the introduction of new state variables coming from the embedding of a phytoplankton growth model in a more classical Redfieldian NNPZD-DOM model (in which the C:N ratio is assumed to be a constant. Following this modelling step, the parameters of the model are estimated using the adjoint data assimilation method which enables the assimilation of chlorophyll and nitrate data sets collected at DYFAMED in 1997.Comparing the predictions of the new Mechanistic model with those of the classical Redfieldian NNPZD-DOM model which was calibrated with the same data sets, we find that both models reproduce the reference data in a comparable manner. Both fluxes and stocks can be equally well predicted by either model. However if the models are coinciding on an average basis, they are diverging from a variability prediction point of view. In the Mechanistic model biology adapts much faster to its environment giving rise to higher short term variations. Moreover the seasonal variability in total production differs from the Redfieldian NNPZD-DOM model to the Mechanistic model. In summer the Mechanistic model predicts higher production values in carbon unit than the Redfieldian NNPZD

  2. Regulatory Technology Development Plan - Sodium Fast Reactor: Mechanistic Source Term - Trial Calculation

    International Nuclear Information System (INIS)

    Grabaskas, David

    2016-01-01

    The potential release of radioactive material during a plant incident, referred to as the source term, is a vital design metric and will be a major focus of advanced reactor licensing. The U.S. Nuclear Regulatory Commission has stated an expectation for advanced reactor vendors to present a mechanistic assessment of the potential source term in their license applications. The mechanistic source term presents an opportunity for vendors to realistically assess the radiological consequences of an incident, and may allow reduced emergency planning zones and smaller plant sites. However, the development of a mechanistic source term for advanced reactors is not without challenges, as there are often numerous phenomena impacting the transportation and retention of radionuclides. This project sought to evaluate U.S. capabilities regarding the mechanistic assessment of radionuclide release from core damage incidents at metal fueled, pool-type sodium fast reactors (SFRs). The purpose of the analysis was to identify, and prioritize, any gaps regarding computational tools or data necessary for the modeling of radionuclide transport and retention phenomena. To accomplish this task, a parallel-path analysis approach was utilized. One path, led by Argonne and Sandia National Laboratories, sought to perform a mechanistic source term assessment using available codes, data, and models, with the goal to identify gaps in the current knowledge base. The second path, performed by an independent contractor, performed sensitivity analyses to determine the importance of particular radionuclides and transport phenomena in regards to offsite consequences. The results of the two pathways were combined to prioritize gaps in current capabilities.

  3. The Combined Use of Correlative and Mechanistic Species Distribution Models Benefits Low Conservation Status Species.

    Directory of Open Access Journals (Sweden)

    Thibaud Rougier

    Full Text Available Species can respond to climate change by tracking appropriate environmental conditions in space, resulting in a range shift. Species Distribution Models (SDMs can help forecast such range shift responses. For few species, both correlative and mechanistic SDMs were built, but allis shad (Alosa alosa, an endangered anadromous fish species, is one of them. The main purpose of this study was to provide a framework for joint analyses of correlative and mechanistic SDMs projections in order to strengthen conservation measures for species of conservation concern. Guidelines for joint representation and subsequent interpretation of models outputs were defined and applied. The present joint analysis was based on the novel mechanistic model GR3D (Global Repositioning Dynamics of Diadromous fish Distribution which was parameterized on allis shad and then used to predict its future distribution along the European Atlantic coast under different climate change scenarios (RCP 4.5 and RCP 8.5. We then used a correlative SDM for this species to forecast its distribution across the same geographic area and under the same climate change scenarios. First, projections from correlative and mechanistic models provided congruent trends in probability of habitat suitability and population dynamics. This agreement was preferentially interpreted as referring to the species vulnerability to climate change. Climate change could not be accordingly listed as a major threat for allis shad. The congruence in predicted range limits between SDMs projections was the next point of interest. The difference, when noticed, required to deepen our understanding of the niche modelled by each approach. In this respect, the relative position of the northern range limit between the two methods strongly suggested here that a key biological process related to intraspecific variability was potentially lacking in the mechanistic SDM. Based on our knowledge, we hypothesized that local

  4. Are Mechanistic and Statistical QSAR Approaches Really Different? MLR Studies on 158 Cycloalkyl-Pyranones.

    Science.gov (United States)

    Bhhatarai, Barun; Garg, Rajni; Gramatica, Paola

    2010-07-12

    Two parallel approaches for quantitative structure-activity relationships (QSAR) are predominant in literature, one guided by mechanistic methods (including read-across) and another by the use of statistical methods. To bridge the gap between these two approaches and to verify their main differences, a comparative study of mechanistically relevant and statistically relevant QSAR models, developed on a case study of 158 cycloalkyl-pyranones, biologically active on inhibition (Ki ) of HIV protease, was performed. Firstly, Multiple Linear Regression (MLR) based models were developed starting from a limited amount of molecular descriptors which were widely proven to have mechanistic interpretation. Then robust and predictive MLR models were developed on the same set using two different statistical approaches unbiased of input descriptors. Development of models based on Statistical I method was guided by stepwise addition of descriptors while Genetic Algorithm based selection of descriptors was used for the Statistical II. Internal validation, the standard error of the estimate, and Fisher's significance test were performed for both the statistical models. In addition, external validation was performed for Statistical II model, and Applicability Domain was verified as normally practiced in this approach. The relationships between the activity and the important descriptors selected in all the models were analyzed and compared. It is concluded that, despite the different type and number of input descriptors, and the applied descriptor selection tools or the algorithms used for developing the final model, the mechanistical and statistical approach are comparable to each other in terms of quality and also for mechanistic interpretability of modelling descriptors. Agreement can be observed between these two approaches and the better result could be a consensus prediction from both the models. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Regulatory Technology Development Plan - Sodium Fast Reactor: Mechanistic Source Term – Trial Calculation

    Energy Technology Data Exchange (ETDEWEB)

    Grabaskas, David [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Bucknor, Matthew [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Jerden, James [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Brunett, Acacia J. [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Denman, Matthew [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Nuclear Engineering Division; Clark, Andrew [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Nuclear Engineering Division; Denning, Richard S. [Consultant, Columbus, OH (United States)

    2016-10-01

    The potential release of radioactive material during a plant incident, referred to as the source term, is a vital design metric and will be a major focus of advanced reactor licensing. The U.S. Nuclear Regulatory Commission has stated an expectation for advanced reactor vendors to present a mechanistic assessment of the potential source term in their license applications. The mechanistic source term presents an opportunity for vendors to realistically assess the radiological consequences of an incident, and may allow reduced emergency planning zones and smaller plant sites. However, the development of a mechanistic source term for advanced reactors is not without challenges, as there are often numerous phenomena impacting the transportation and retention of radionuclides. This project sought to evaluate U.S. capabilities regarding the mechanistic assessment of radionuclide release from core damage incidents at metal fueled, pool-type sodium fast reactors (SFRs). The purpose of the analysis was to identify, and prioritize, any gaps regarding computational tools or data necessary for the modeling of radionuclide transport and retention phenomena. To accomplish this task, a parallel-path analysis approach was utilized. One path, led by Argonne and Sandia National Laboratories, sought to perform a mechanistic source term assessment using available codes, data, and models, with the goal to identify gaps in the current knowledge base. The second path, performed by an independent contractor, performed sensitivity analyses to determine the importance of particular radionuclides and transport phenomena in regards to offsite consequences. The results of the two pathways were combined to prioritize gaps in current capabilities.

  6. MISR Views Hurricane Carlotta

    Science.gov (United States)

    2000-01-01

    With winds reaching 155 mph, this year's Hurricane Carlotta became the second strongest eastern Pacific June hurricane on record. These images from MISR show the hurricane on June 21, the day of its peak intensity. The pictures are oriented so that the spacecraft's flight path is from left to right; north is at the left.The top image is a color view from MISR's vertical (nadir) camera, showing Carlotta's location in the eastern Pacific Ocean, about 500 km south of Puerto Vallarta, Mexico.The middle image is a stereoscopic 'anaglyph' created using MISR's nadir camera plus one of its aftward-viewing cameras, and shows a closer view of the area around the hurricane. Viewing with red/blue glasses (red filter over the left eye) is required to obtain a 3-D stereo effect.Near the center of the storm, the eye is about 25 km in diameter and partially obscured by a thin cloud. About 50 km to the left of the eye, the sharp drop-off from high-level to low-level cloud gives a sense of the vertical extent of the hidden eye wall. The low-level cloud is spiraling counterclockwise into the center of the cyclone. It then rises in the vicinity of the eye wall and emerges with a clockwise rotation at high altitude. Maximum surface winds are found near the eye wall.The bottom stereo image is a zoomed-in view of convective clouds in the hurricane's spiral arms. The arms are breeding grounds for severe thunderstorms, with associated heavy rain and flooding, frequent lightning, and tornadoes. Thunderstorms rise in dramatic fashion to about the same altitude as the high cloud near the hurricane's center, and are made up of individual cells that are typically less than 20 km in diameter. This image shows a number of these cells, some fairly isolated, and others connected together. Their three-dimensional structure is clearly apparent in this stereo view.MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The

  7. Multi-view point splatting

    OpenAIRE

    Hübner, T; Zhang, Y; Pajarola, R

    2006-01-01

    The fundamental drawback of current stereo and multi-view visualization is the necessity to perform multi pass rendering (one pass for each view) and subsequent image composition + masking for generating multiple stereo views. Thus the rendering time increases in general linearly with the number of views. In this paper we introduce a new method for multi-view splatting based on deferred blending. Our method exploits the programmability of modern graphic processing units (...

  8. Concert Viewing Headphones

    Directory of Open Access Journals (Sweden)

    Kazuya Atsuta

    2011-01-01

    Full Text Available An audiovisual interface equipped with a projector, an inclina-tion sensor, and a distance sensor for zoom control has been developed that enables a user to selectively view and listen to specific performers in a video-taped group performance. Dubbed Concert Viewing Headphones, it has both image and sound processing functions. The image processing extracts the portion of the image indicated by the user and projects it free of distortion on the front and side walls. The sound processing creates imaginary microphones for those performers without one so that the user can hear the sound from any performer. Testing using images and sounds captured using a fisheye-lens camera and 37 lavalier microphones showed that sound locali-zation was fastest when an inverse square function was used for the sound mixing and that the zoom function was useful for locating the desired sound performance.

  9. Hot section viewing system

    Energy Technology Data Exchange (ETDEWEB)

    Morey, W.W.

    1984-09-01

    This report covers the development and testing of a prototype combustor viewing system. The system allows one to see and record images from the inside of an operating gas turbine combustor. The program proceeded through planned phases of conceptual design, preliminary testing to resolve problem areas, prototype design and fabrication, and rig testing. Successful tests were completed with the viewing system in the laboratory, in a high pressure combustor rig, and on a Pratt and Whitney PW20307 jet engine. Both film and video recordings were made during the tests. Digital image analysis techniques were used to enhance images and bring out special effects. The use of pulsed laser illumination was also demonstrated as a means for observing liner surfaces in the presence of luminous flame.

  10. Principal component analysis (PCA of volatile terpene compounds dataset emitted by genetically modified sweet orange fruits and juices in which a D-limonene synthase was either up- or down-regulated vs. empty vector controls

    Directory of Open Access Journals (Sweden)

    Ana Rodríguez

    2016-12-01

    Full Text Available We have categorized the dataset from content and emission of terpene volatiles of peel and juice in both Navelina and Pineapple sweet orange cultivars in which D-limonene was either up- (S, down-regulated (AS or non-altered (EV; control (“Impact of D-limonene synthase up- or down-regulation on sweet orange fruit and juice odor perception”(A. Rodríguez, J.E. Peris, A. Redondo, T. Shimada, E. Costell, I. Carbonell, C. Rojas, L. Peña, (2016 [1]. Data from volatile identification and quantification by HS-SPME and GC–MS were classified by Principal Component Analysis (PCA individually or as chemical groups. AS juice was characterized by the higher influence of the oxygen fraction, and S juice by the major influence of ethyl esters. S juices emitted less linalool compared to AS and EV juices.

  11. Proposed key characteristics of male reproductive toxicants as a method for organizing and screening mechanistic evidence for non-cancer outcomes.

    Science.gov (United States)

    The adoption of systematic review practices for risk assessment includes integration of evidence obtained from experimental, epidemiological, and mechanistic studies. Although mechanistic evidence plays an important role in mode of action analysis, the process of sorting and anal...

  12. Viewing Age: Lifespan Identity and Television Viewing Choices.

    Science.gov (United States)

    Harwood, Jake

    1997-01-01

    Introduces a theoretical perspective on media viewing choices, grounded in social identity theory. Content analysis demonstrates that child, younger adult, and older adult television viewers show a preference for viewing characters of their own age. The experiment demonstrates that young adults' preference for viewing young adult characters exists…

  13. How phenyl makes a difference: mechanistic insights into the ruthenium( ii )-catalysed isomerisation of allylic alcohols

    KAUST Repository

    Manzini, Simone

    2013-10-16

    [RuCl(η5-3-phenylindenyl)(PPh3)2] (1) has been shown to be a highly active catalyst for the isomerisation of allylic alcohols to the corresponding ketones. A variety of substrates undergo the transformation, typically with 0.25-0.5 mol% of catalyst at room temperature, outperforming commonly-used complexes such as [RuCl(Cp)(PPh3) 2] and [RuCl(η5-indenyl)(PPh3) 2]. Mechanistic experiments and density functional theory have been employed to investigate the mechanism and understand the effect of catalyst structure on reactivity. These investigations suggest a oxo-π-allyl mechanism is in operation, avoiding intermediate ruthenium hydride complexes and leading to a characteristic 1,3-deuterium shift. Important mechanistic insights from DFT and experiments also allowed for the design of a protocol that expands the scope of the transformation to include primary allylic alcohols. © 2013 The Royal Society of Chemistry.

  14. Organic chemistry. A data-intensive approach to mechanistic elucidation applied to chiral anion catalysis.

    Science.gov (United States)

    Milo, Anat; Neel, Andrew J; Toste, F Dean; Sigman, Matthew S

    2015-02-13

    Knowledge of chemical reaction mechanisms can facilitate catalyst optimization, but extracting that knowledge from a complex system is often challenging. Here, we present a data-intensive method for deriving and then predictively applying a mechanistic model of an enantioselective organic reaction. As a validating case study, we selected an intramolecular dehydrogenative C-N coupling reaction, catalyzed by chiral phosphoric acid derivatives, in which catalyst-substrate association involves weak, noncovalent interactions. Little was previously understood regarding the structural origin of enantioselectivity in this system. Catalyst and substrate substituent effects were probed by means of systematic physical organic trend analysis. Plausible interactions between the substrate and catalyst that govern enantioselectivity were identified and supported experimentally, indicating that such an approach can afford an efficient means of leveraging mechanistic insight so as to optimize catalyst design. Copyright © 2015, American Association for the Advancement of Science.

  15. Mechanistic modelling of cancer: some reflections from software engineering and philosophy of science.

    Science.gov (United States)

    Cañete-Valdeón, José M; Wieringa, Roel; Smallbone, Kieran

    2012-12-01

    There is a growing interest in mathematical mechanistic modelling as a promising strategy for understanding tumour progression. This approach is accompanied by a methodological change of making research, in which models help to actively generate hypotheses instead of waiting for general principles to become apparent once sufficient data are accumulated. This paper applies recent research from philosophy of science to uncover three important problems of mechanistic modelling which may compromise its mainstream application, namely: the dilemma of formal and informal descriptions, the need to express degrees of confidence and the need of an argumentation framework. We report experience and research on similar problems from software engineering and provide evidence that the solutions adopted there can be transferred to the biological domain. We hope this paper can provoke new opportunities for further and profitable interdisciplinary research in the field.

  16. An improved mechanistic critical heat flux model for subcooled flow boiling

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Young Min [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); Chang, Soon Heung [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

    1997-12-31

    Based on the bubble coalescence adjacent to the heated wall as a flow structure for CHF condition, Chang and Lee developed a mechanistic critical heat flux (CHF) model for subcooled flow boiling. In this paper, improvements of Chang-Lee model are implemented with more solid theoretical bases for subcooled and low-quality flow boiling in tubes. Nedderman-Shearer`s equations for the skin friction factor and universal velocity profile models are employed. Slip effect of movable bubbly layer is implemented to improve the predictability of low mass flow. Also, mechanistic subcooled flow boiling model is used to predict the flow quality and void fraction. The performance of the present model is verified using the KAIST CHF database of water in uniformly heated tubes. It is found that the present model can give a satisfactory agreement with experimental data within less than 9% RMS error. 9 refs., 5 figs. (Author)

  17. Mechanistic modelling of fluidized bed drying processes of wet porous granules

    DEFF Research Database (Denmark)

    Mortier, Séverine Thérèse F.C.; De Beer, Thomas; Gernaey, Krist

    2011-01-01

    granules is given. This review provides a basis for future mechanistic model development for the drying process of wet granules in pharmaceutical processes. It is intended for a broad audience with a varying level of knowledge on pharmaceutical processes and mathematical modelling. Mathematical models...... particle, can be described using the continuum approach, the pore network modelling method and the shrinkage of the diameter of the wet core approach. As several granules dry at a drying rate dependent on the gas temperature, gas velocity, porosity, etc., the moisture content of a batch of granules......Fluidized bed dryers are frequently used in industrial applications and also in the pharmaceutical industry. The general incentives to develop mechanistic models for pharmaceutical processes are listed, and our vision on how this can particularly be done for fluidized bed drying processes of wet...

  18. Synthesis, Cytotoxicity and Mechanistic Evaluation of 4-Oxoquinoline-3-carboxamide Derivatives: Finding New Potential Anticancer Drugs

    Directory of Open Access Journals (Sweden)

    Luana da S. M. Forezi

    2014-05-01

    Full Text Available As part of a continuing search for new potential anticancer candidates, we describe the synthesis, cytotoxicity and mechanistic evaluation of a series of 4-oxoquinoline-3-carboxamide derivatives as novel anticancer agents. The inhibitory activity of compounds 10–18 was determined against three cancer cell lines using the MTT colorimetric assay. The screening revealed that derivatives 16b and 17b exhibited significant cytotoxic activity against the gastric cancer cell line but was not active against a normal cell line, in contrast to doxorubicin, a standard chemotherapeutic drug in clinical use. Interestingly, no hemolytical activity was observed when the toxicity of 16b and 17b was tested against blood cells. The in silico and in vitro mechanistic evaluation indicated the potential of 16b as a lead for the development of novel anticancer agents against gastric cancer cells.

  19. Safety, Efficacy, and Mechanistic Studies Regarding Citrus aurantium (Bitter Orange) Extract and p‐Synephrine

    OpenAIRE

    Stohs, Sidney J.

    2017-01-01

    Citrus aurantium L. (bitter orange) extracts that contain p‐synephrine as the primary protoalkaloid are widely used for weight loss/weight management, sports performance, appetite control, energy, and mental focus and cognition. Questions have been raised about the safety of p‐synephrine because it has some structural similarity to ephedrine. This review focuses on current human, animal, in vitro, and mechanistic studies that address the safety, efficacy, and mechanisms of action of bitter or...

  20. Topographic characterization of polymer materials at different length scales and the mechanistic understanding of wetting phenomena

    OpenAIRE

    Calvimontes, Alfredo

    2010-01-01

    The present study suggests new insights into topographic characterisation of engineering polymer surfaces towards to physical-chemical and mechanistic understanding of wetting phenomena on rough surfaces. Non-contact chromatic confocal imaging was chosen and justified as the optimal measuring method to study and correlate surface topography and surface properties of Sheet Moulding Compounds (SMC) as well as polyester and cotton fabrics. Before topographical characterisation, an adequate se...

  1. The mechanistic causes of peripheral intravenous catheter failure based on a parametric computational study

    OpenAIRE

    Piper, Russell; Carr, Peter J.; Kelsey, Lachlan J.; Bulmer, Andrew C.; Keogh, Samantha; Doyle, Barry J.

    2018-01-01

    Peripheral intravenous catheters (PIVCs) are the most commonly used invasive medical device, yet up to 50% fail. Many pathways to failure are mechanistic and related to fluid mechanics, thus can be investigated using computational fluid dynamics (CFD). Here we used CFD to investigate typical PIVC parameters (infusion rate, catheter size, insertion angle and tip position) and report the hemodynamic environment (wall shear stress (WSS), blood damage, particle residence time and venous stasis vo...

  2. Use of Fluorinated Functionality in Enzyme Inhibitor Development: Mechanistic and Analytical Advantages

    OpenAIRE

    Berkowitz, David B.; Karukurichi, Kannan R.; de la Salud-Bea, Roberto; Nelson, David L.; McCune, Christopher D.

    2008-01-01

    On the one hand, owing to its electronegativity, relatively small size, and notable leaving group ability from anionic intermediates, fluorine offers unique opportunities for mechanism-based enzyme inhibitor design. On the other, the “bio-orthogonal” and NMR-active 19-fluorine nucleus allows the bioorganic chemist to follow the mechanistic fate of fluorinated substrate analogues or inhibitors as they are enzymatically processed. This article takes an overview of the field, highlighting key de...

  3. Defining Glomerular Disease in Mechanistic Terms: Implementing an Integrative Biology Approach in Nephrology

    OpenAIRE

    Mariani, Laura H.; Pendergraft, William F.; Kretzler, Matthias

    2016-01-01

    Advances in biomedical research allow for the capture of an unprecedented level of genetic, molecular, and clinical information from large patient cohorts, where the quest for precision medicine can be pursued. An overarching goal of precision medicine is to integrate the large–scale genetic and molecular data with deep phenotypic information to identify a new mechanistic disease classification. This classification can ideally be used to meet the clinical goal of the right medication for the ...

  4. Mechanistic rationalization of unusual sigmoidal kinetic profiles in the Machetti-De Sarlo cycloaddition reaction.

    Science.gov (United States)

    Mower, Matthew P; Blackmond, Donna G

    2015-02-18

    Unusual sigmoidal kinetic profiles in the Machetti-De Sarlo base-catalyzed 1,3-dipolar cycloaddition of acrylamide to N-methylnitroacetamide are rationalized by detailed in situ kinetic analysis. A dual role is uncovered in which a substrate acts as a precursor to catalyze its own reaction. Such kinetic studies provide a general protocol for distinguishing among different mechanistic origins of induction periods in complex organic reactions.

  5. Mechanistic Oral Absorption Modeling and Simulation for Formulation Development and Bioequivalence Evaluation: Report of an FDA Public Workshop

    Science.gov (United States)

    Duan, J; Kesisoglou, F; Novakovic, J; Amidon, GL; Jamei, M; Lukacova, V; Eissing, T; Tsakalozou, E; Zhao, L; Lionberger, R

    2017-01-01

    On May 19, 2016, the US Food and Drug Administration (FDA) hosted a public workshop, entitled “Mechanistic Oral Absorption Modeling and Simulation for Formulation Development and Bioequivalence Evaluation.”1 The topic of mechanistic oral absorption modeling, which is one of the major applications of physiologically based pharmacokinetic (PBPK) modeling and simulation, focuses on predicting oral absorption by mechanistically integrating gastrointestinal transit, dissolution, and permeation processes, incorporating systems, active pharmaceutical ingredient (API), and the drug product information, into a systemic mathematical whole‐body framework.2 PMID:28571121

  6. Infanticide: contrasting views.

    Science.gov (United States)

    Spinelli, M G

    2005-05-01

    The subject of infanticide is met with complex reactions. Paradoxically, the very same society that practices gender selection may also prosecute a mother for killing an infant. The author reviews historical, cultural, and political views on infanticide. Using the case of Andrea Yates, the author illustrates the outcome of an infanticide case in American Judicial System in which a floridly psychotic mother serves a life in prison. This work explores contemporary worldwide experiences of infanticide and investigates culture specific attitudes towards causes, facilitation, and punishment of this tragic cause of infant mortality. The work illustrates the intricate relationship between a society's construction of parenthood and mothering, and its experience of infanticide. Infanticide is deeply embedded in, and responsive to the societies in which it occurs. Causes vary from poverty to stigma, dowry and insanity. The worldwide experience of infant murder reaches from facilitation of gender determination in China and Asia to lethal execution of mothers as perpetrators in the United States. Infanticide must be viewed against the political, cultural, social and legal backgrounds of societies that treat women with disregard. It is a reflection of social and cultural norms governing motherhood, a constant that links these seemingly disparate acts. The overall association of infanticide with crime, postpartum illness, population and sex selection speaks to unjust discrimination against women and children. We as a world society can do a far better job of protecting motherhood.

  7. Ultrasonic viewing device

    International Nuclear Information System (INIS)

    Ito, Juro.

    1979-01-01

    Purpose: To improve the safety of reactor operation by enabling to detect the states and positions of fuel assemblies over a wide range with a set of ultrasonic viewing device comprising a rotatable ultrasonic transmitter-receiver and a reflector mounted with an adjustable angle. Constitution: A driving portion for a ultrasonic viewing device is provided to a rotary plug closing the opening of a reactor vessel and a guide pipe suspending below the coolant level is provided to the driving portion. An ultrasonic transmitter-receiver is provided at the end of the holder tube in the guide pipe. A reflector is provided at the upper position of the reactor core so as to correspond to the ultrasonic transmitter-receiver. The ultrasonic transmitter-receiver, positioned by the driving portion, performs horizontal movement for scanning the entire surface of the top of the reactor core, as well as vertical movement covering the gap between the upper mechanism on the reactor and the reactor core, whereby the confirmation for the separation of the control rod and the detection for the states of the reactor core can be conducted by the reflection waves from the reflector. (Moriyama, K.)

  8. Exploiting Bioprocessing Fluctuations to Elicit the Mechanistics of De Novo Lipogenesis in Yarrowia lipolytica.

    Directory of Open Access Journals (Sweden)

    Andreas E Vasdekis

    Full Text Available Despite substantial achievements in elucidating the metabolic pathways of lipogenesis, a mechanistic representation of lipid accumulation and degradation has not been fully attained to-date. Recent evidence suggests that lipid accumulation can occur through increases of either the cytosolic copy-number of lipid droplets (LDs, or the LDs size. However, the prevailing phenotype, or how such mechanisms pertain to lipid degradation remain poorly understood. To address this shortcoming, we employed the-recently discovered-innate bioprocessing fluctuations in Yarrowia lipolytica, and performed single-cell fluctuation analysis using optical microscopy and microfluidics that generate a quasi-time invariant microenvironment. We report that lipid accumulation at early stationary phase in rich medium is substantially more likely to occur through variations in the LDs copy-number, rather than the LDs size. Critically, these mechanistics are also preserved during lipid degradation, as well as upon exposure to a protein translation inhibitor. The latter condition additionally induced a lipid accumulation phase, accompanied by the downregulation of lipid catabolism. Our results enable an in-depth mechanistic understanding of lipid biogenesis, and expand longitudinal single-cell fluctuation analyses from gene regulation to metabolism.

  9. Exploiting Bioprocessing Fluctuations to Elicit the Mechanistics of De Novo Lipogenesis in Yarrowia lipolytica.

    Science.gov (United States)

    Vasdekis, Andreas E; Silverman, Andrew M; Stephanopoulos, Gregory

    2017-01-01

    Despite substantial achievements in elucidating the metabolic pathways of lipogenesis, a mechanistic representation of lipid accumulation and degradation has not been fully attained to-date. Recent evidence suggests that lipid accumulation can occur through increases of either the cytosolic copy-number of lipid droplets (LDs), or the LDs size. However, the prevailing phenotype, or how such mechanisms pertain to lipid degradation remain poorly understood. To address this shortcoming, we employed the-recently discovered-innate bioprocessing fluctuations in Yarrowia lipolytica, and performed single-cell fluctuation analysis using optical microscopy and microfluidics that generate a quasi-time invariant microenvironment. We report that lipid accumulation at early stationary phase in rich medium is substantially more likely to occur through variations in the LDs copy-number, rather than the LDs size. Critically, these mechanistics are also preserved during lipid degradation, as well as upon exposure to a protein translation inhibitor. The latter condition additionally induced a lipid accumulation phase, accompanied by the downregulation of lipid catabolism. Our results enable an in-depth mechanistic understanding of lipid biogenesis, and expand longitudinal single-cell fluctuation analyses from gene regulation to metabolism.

  10. Mechanistic equivalent circuit modelling of a commercial polymer electrolyte membrane fuel cell

    Science.gov (United States)

    Giner-Sanz, J. J.; Ortega, E. M.; Pérez-Herranz, V.

    2018-03-01

    Electrochemical impedance spectroscopy (EIS) has been widely used in the fuel cell field since it allows deconvolving the different physic-chemical processes that affect the fuel cell performance. Typically, EIS spectra are modelled using electric equivalent circuits. In this work, EIS spectra of an individual cell of a commercial PEM fuel cell stack were obtained experimentally. The goal was to obtain a mechanistic electric equivalent circuit in order to model the experimental EIS spectra. A mechanistic electric equivalent circuit is a semiempirical modelling technique which is based on obtaining an equivalent circuit that does not only correctly fit the experimental spectra, but which elements have a mechanistic physical meaning. In order to obtain the aforementioned electric equivalent circuit, 12 different models with defined physical meanings were proposed. These equivalent circuits were fitted to the obtained EIS spectra. A 2 step selection process was performed. In the first step, a group of 4 circuits were preselected out of the initial list of 12, based on general fitting indicators as the determination coefficient and the fitted parameter uncertainty. In the second step, one of the 4 preselected circuits was selected on account of the consistency of the fitted parameter values with the physical meaning of each parameter.

  11. INTEGRATION OF QSAR AND SAR METHODS FOR THE MECHANISTIC INTERPRETATION OF PREDICTIVE MODELS FOR CARCINOGENICITY

    Directory of Open Access Journals (Sweden)

    Natalja Fjodorova

    2012-07-01

    Full Text Available The knowledge-based Toxtree expert system (SAR approach was integrated with the statistically based counter propagation artificial neural network (CP ANN model (QSAR approach to contribute to a better mechanistic understanding of a carcinogenicity model for non-congeneric chemicals using Dragon descriptors and carcinogenic potency for rats as a response. The transparency of the CP ANN algorithm was demonstrated using intrinsic mapping technique specifically Kohonen maps. Chemical structures were represented by Dragon descriptors that express the structural and electronic features of molecules such as their shape and electronic surrounding related to reactivity of molecules. It was illustrated how the descriptors are correlated with particular structural alerts (SAs for carcinogenicity with recognized mechanistic link to carcinogenic activity. Moreover, the Kohonen mapping technique enables one to examine the separation of carcinogens and non-carcinogens (for rats within a family of chemicals with a particular SA for carcinogenicity. The mechanistic interpretation of models is important for the evaluation of safety of chemicals.

  12. Mechanistic effect modeling for ecological risk assessment: where to go from here?

    Science.gov (United States)

    Grimm, Volker; Martin, Benjamin T

    2013-07-01

    Mechanistic effect models (MEMs) consider the mechanisms of how chemicals affect individuals and ecological systems such as populations and communities. There is an increasing awareness that MEMs have high potential to make risk assessment of chemicals more ecologically relevant than current standard practice. Here we discuss what kinds of MEMs are needed to improve scientific and regulatory aspects of risk assessment. To make valid predictions for a wide range of environmental conditions, MEMs need to include a sufficient amount of emergence, for example, population dynamics emerging from what individual organisms do. We present 1 example where the life cycle of individuals is described using Dynamic Energy Budget theory. The resulting individual-based population model is thus parameterized at the individual level but correctly predicts multiple patterns at the population level. This is the case for both control and treated populations. We conclude that the state-of-the-art in mechanistic effect modeling has reached a level where MEMs are robust and predictive enough to be used in regulatory risk assessment. Mechanistic effect models will thus be used to advance the scientific basis of current standard practice and will, if their development follows Good Modeling Practice, be included in a standardized way in future regulatory risk assessments. Copyright © 2013 SETAC.

  13. Mechanistic Resolution Required to Mediate Operant Learned Behaviors: Insights from Neuronal Ensemble-Specific Inactivation

    Directory of Open Access Journals (Sweden)

    Bruce T. Hope

    2017-04-01

    Full Text Available Many learned behaviors are directed by complex sets of highly specific stimuli or cues. The neural mechanisms mediating learned associations in these behaviors must be capable of storing complex cue information and distinguishing among different learned associations—we call this general concept “mechanistic resolution”. For many years, our understanding of the circuitry of these learned behaviors has been based primarily on inactivation of specific cell types or whole brain areas regardless of which neurons were activated during the cue-specific behaviors. However, activation of all cells or specific cell types in a brain area do not have enough mechanistic resolution to encode or distinguish high-resolution learned associations in these behaviors. Instead, these learned associations are likely encoded within specific patterns of sparsely distributed neurons called neuronal ensembles that are selectively activated by the cues. This review article focuses on studies of neuronal ensembles in operant learned responding to obtain food or drug rewards. These studies suggest that the circuitry of operant learned behaviors may need to be re-examined using ensemble-specific manipulations that have the requisite level of mechanistic resolution.

  14. Mechanistic model of mass-specific basal metabolic rate: evaluation in healthy young adults.

    Science.gov (United States)

    Wang, Z; Bosy-Westphal, A; Schautz, B; Müller, M

    2011-12-01

    Mass-specific basal metabolic rate (mass-specific BMR), defined as the resting energy expenditure per unit body mass per day, is an important parameter in energy metabolism research. However, a mechanistic explanation for magnitude of mass-specific BMR remains lacking. The objective of the present study was to validate the applicability of a proposed mass-specific BMR model in healthy adults. A mechanistic model was developed at the organ-tissue level, mass-specific BMR = Σ( K i × F i ), where Fi is the fraction of body mass as individual organs and tissues, and K i is the specific resting metabolic rate of major organs and tissues. The Fi values were measured by multiple MRI scans and the K i values were suggested by Elia in 1992. A database of healthy non-elderly non-obese adults (age 20 - 49 yrs, BMI BMR of all subjects was 21.6 ± 1.9 (mean ± SD) and 21.7 ± 1.6 kcal/kg per day, respectively. The measured mass-specific BMR was correlated with the predicted mass-specific BMR (r = 0.82, P BMR, versus the average of measured and predicted mass-specific BMR. In conclusion, the proposed mechanistic model was validated in non-elderly non-obese adults and can help to understand the inherent relationship between mass-specific BMR and body composition.

  15. Comparative evaluation of statistical and mechanistic models of Escherichia coli at beaches in southern Lake Michigan

    Science.gov (United States)

    Safaie, Ammar; Wendzel, Aaron; Ge, Zhongfu; Nevers, Meredith; Whitman, Richard L.; Corsi, Steven R.; Phanikumar, Mantha S.

    2016-01-01

    Statistical and mechanistic models are popular tools for predicting the levels of indicator bacteria at recreational beaches. Researchers tend to use one class of model or the other, and it is difficult to generalize statements about their relative performance due to differences in how the models are developed, tested, and used. We describe a cooperative modeling approach for freshwater beaches impacted by point sources in which insights derived from mechanistic modeling were used to further improve the statistical models and vice versa. The statistical models provided a basis for assessing the mechanistic models which were further improved using probability distributions to generate high-resolution time series data at the source, long-term “tracer” transport modeling based on observed electrical conductivity, better assimilation of meteorological data, and the use of unstructured-grids to better resolve nearshore features. This approach resulted in improved models of comparable performance for both classes including a parsimonious statistical model suitable for real-time predictions based on an easily measurable environmental variable (turbidity). The modeling approach outlined here can be used at other sites impacted by point sources and has the potential to improve water quality predictions resulting in more accurate estimates of beach closures.

  16. Mechanistic Systems Modeling to Improve Understanding and Prediction of Cardiotoxicity Caused by Targeted Cancer Therapeutics

    Directory of Open Access Journals (Sweden)

    Jaehee V. Shim

    2017-09-01

    Full Text Available Tyrosine kinase inhibitors (TKIs are highly potent cancer therapeutics that have been linked with serious cardiotoxicity, including left ventricular dysfunction, heart failure, and QT prolongation. TKI-induced cardiotoxicity is thought to result from interference with tyrosine kinase activity in cardiomyocytes, where these signaling pathways help to control critical processes such as survival signaling, energy homeostasis, and excitation–contraction coupling. However, mechanistic understanding is limited at present due to the complexities of tyrosine kinase signaling, and the wide range of targets inhibited by TKIs. Here, we review the use of TKIs in cancer and the cardiotoxicities that have been reported, discuss potential mechanisms underlying cardiotoxicity, and describe recent progress in achieving a more systematic understanding of cardiotoxicity via the use of mechanistic models. In particular, we argue that future advances are likely to be enabled by studies that combine large-scale experimental measurements with Quantitative Systems Pharmacology (QSP models describing biological mechanisms and dynamics. As such approaches have proven extremely valuable for understanding and predicting other drug toxicities, it is likely that QSP modeling can be successfully applied to cardiotoxicity induced by TKIs. We conclude by discussing a potential strategy for integrating genome-wide expression measurements with models, illustrate initial advances in applying this approach to cardiotoxicity, and describe challenges that must be overcome to truly develop a mechanistic and systematic understanding of cardiotoxicity caused by TKIs.

  17. Emergent Global Patterns of Ecosystem Structure and Function from a Mechanistic General Ecosystem Model

    Science.gov (United States)

    Emmott, Stephen; Hutton, Jon; Lyutsarev, Vassily; Smith, Matthew J.; Scharlemann, Jörn P. W.; Purves, Drew W.

    2014-01-01

    Anthropogenic activities are causing widespread degradation of ecosystems worldwide, threatening the ecosystem services upon which all human life depends. Improved understanding of this degradation is urgently needed to improve avoidance and mitigation measures. One tool to assist these efforts is predictive models of ecosystem structure and function that are mechanistic: based on fundamental ecological principles. Here we present the first mechanistic General Ecosystem Model (GEM) of ecosystem structure and function that is both global and applies in all terrestrial and marine environments. Functional forms and parameter values were derived from the theoretical and empirical literature where possible. Simulations of the fate of all organisms with body masses between 10 µg and 150,000 kg (a range of 14 orders of magnitude) across the globe led to emergent properties at individual (e.g., growth rate), community (e.g., biomass turnover rates), ecosystem (e.g., trophic pyramids), and macroecological scales (e.g., global patterns of trophic structure) that are in general agreement with current data and theory. These properties emerged from our encoding of the biology of, and interactions among, individual organisms without any direct constraints on the properties themselves. Our results indicate that ecologists have gathered sufficient information to begin to build realistic, global, and mechanistic models of ecosystems, capable of predicting a diverse range of ecosystem properties and their response to human pressures. PMID:24756001

  18. Fast, simultaneous simulation of the integrated urban wastewater system using mechanistic surrogate models.

    Science.gov (United States)

    Meirlaen, J; Huyghebaert, B; Sforzi, F; Benedetti, L; Vanrolleghem, P

    2001-01-01

    The urban wastewater system components (sewer, treatment plant, and river) are often modelled using complex mechanistic models. Mechanistic surrogate models are introduced here as simplified models that still contain some physical knowledge. Surrogate models are faster, but are less but still sufficiently accurate, and require more data to be calibrated. The possibilities of replacing actual field data by virtual data generated with a complex mechanistic model for calibration of the surrogate model are examined. As an example, a series of tanks with variable volume is shown to approximate sufficiently well the flow propagation in the river Zwalm (Belgium) as predicted by the "de Saint-Venant" equations. The three surrogate models can be implemented in the WEST simulator, which makes a simultaneous simulation of the system possible. In this work a connection is made between the ASM1 and the new IWA River Model No. 1 (RWOM1) by using a translator between the models in such a way that both mass and elemental balances remain closed for the overall system. This approach is illustrated with a case study on the river Lambro (Italy). The dispersion process in this river with steady flow could be modelled by using a tanks in series model, while the water quality in the river was predicted to improve substantially with an increase in hydraulic capacity of the treatment plant. The simulation results with the upgraded plant still need to be checked by field data.

  19. Integration of QSAR and SAR methods for the mechanistic interpretation of predictive models for carcinogenicity

    Directory of Open Access Journals (Sweden)

    Natalja Fjodorova

    2012-07-01

    Full Text Available The knowledge-based Toxtree expert system (SAR approach was integrated with the statistically based counter propagation artificial neural network (CP ANN model (QSAR approach to contribute to a better mechanistic understanding of a carcinogenicity model for non-congeneric chemicals using Dragon descriptors and carcinogenic potency for rats as a response. The transparency of the CP ANN algorithm was demonstrated using intrinsic mapping technique specifically Kohonen maps. Chemical structures were represented by Dragon descriptors that express the structural and electronic features of molecules such as their shape and electronic surrounding related to reactivity of molecules. It was illustrated how the descriptors are correlated with particular structural alerts (SAs for carcinogenicity with recognized mechanistic link to carcinogenic activity. Moreover, the Kohonen mapping technique enables one to examine the separation of carcinogens and non-carcinogens (for rats within a family of chemicals with a particular SA for carcinogenicity. The mechanistic interpretation of models is important for the evaluation of safety of chemicals.

  20. Real-time forecasting of infectious disease dynamics with a stochastic semi-mechanistic model.

    Science.gov (United States)

    Funk, Sebastian; Camacho, Anton; Kucharski, Adam J; Eggo, Rosalind M; Edmunds, W John

    2018-03-01

    Real-time forecasts of infectious diseases can help public health planning, especially during outbreaks. If forecasts are generated from mechanistic models, they can be further used to target resources or to compare the impact of possible interventions. However, paremeterising such models is often difficult in real time, when information on behavioural changes, interventions and routes of transmission are not readily available. Here, we present a semi-mechanistic model of infectious disease dynamics that was used in real time during the 2013-2016 West African Ebola epidemic, and show fits to a Ebola Forecasting Challenge conducted in late 2015 with simulated data mimicking the true epidemic. We assess the performance of the model in different situations and identify strengths and shortcomings of our approach. Models such as the one presented here which combine the power of mechanistic models with the flexibility to include uncertainty about the precise outbreak dynamics may be an important tool in combating future outbreaks. Copyright © 2016 The Author(s). Published by Elsevier B.V. All rights reserved.

  1. Side-View Face Recognition

    NARCIS (Netherlands)

    Santemiz, P.; Spreeuwers, Lieuwe Jan; Veldhuis, Raymond N.J.

    2010-01-01

    Side-view face recognition is a challenging problem with many applications. Especially in real-life scenarios where the environment is uncontrolled, coping with pose variations up to side-view positions is an important task for face recognition. In this paper we discuss the use of side view face

  2. Mechanistic models

    Energy Technology Data Exchange (ETDEWEB)

    Curtis, S.B.

    1990-09-01

    Several models and theories are reviewed that incorporate the idea of radiation-induced lesions (repairable and/or irreparable) that can be related to molecular lesions in the DNA molecule. Usually the DNA double-strand or chromatin break is suggested as the critical lesion. In the models, the shoulder on the low-LET survival curve is hypothesized as being due to one (or more) of the following three mechanisms: (1) ``interaction`` of lesions produced by statistically independent particle tracks; (2) nonlinear (i.e., linear-quadratic) increase in the yield of initial lesions, and (3) saturation of repair processes at high dose. Comparisons are made between the various approaches. Several significant advances in model development are discussed; in particular, a description of the matrix formulation of the Markov versions of the RMR and LPL models is given. The more advanced theories have incorporated statistical fluctuations in various aspects of the energy-loss and lesion-formation process. An important direction is the inclusion of physical and chemical processes into the formulations by incorporating relevant track structure theory (Monte Carlo track simulations) and chemical reactions of radiation-induced radicals. At the biological end, identification of repair genes and how they operate as well as a better understanding of how DNA misjoinings lead to lethal chromosome aberrations are needed for appropriate inclusion into the theories. More effort is necessary to model the complex end point of radiation-induced carcinogenesis.

  3. Mechanistic models

    Energy Technology Data Exchange (ETDEWEB)

    Curtis, S.B.

    1990-09-01

    Several models and theories are reviewed that incorporate the idea of radiation-induced lesions (repairable and/or irreparable) that can be related to molecular lesions in the DNA molecule. Usually the DNA double-strand or chromatin break is suggested as the critical lesion. In the models, the shoulder on the low-LET survival curve is hypothesized as being due to one (or more) of the following three mechanisms: (1) interaction'' of lesions produced by statistically independent particle tracks; (2) nonlinear (i.e., linear-quadratic) increase in the yield of initial lesions, and (3) saturation of repair processes at high dose. Comparisons are made between the various approaches. Several significant advances in model development are discussed; in particular, a description of the matrix formulation of the Markov versions of the RMR and LPL models is given. The more advanced theories have incorporated statistical fluctuations in various aspects of the energy-loss and lesion-formation process. An important direction is the inclusion of physical and chemical processes into the formulations by incorporating relevant track structure theory (Monte Carlo track simulations) and chemical reactions of radiation-induced radicals. At the biological end, identification of repair genes and how they operate as well as a better understanding of how DNA misjoinings lead to lethal chromosome aberrations are needed for appropriate inclusion into the theories. More effort is necessary to model the complex end point of radiation-induced carcinogenesis.

  4. Incorporation of lysosomal sequestration in the mechanistic model for prediction of tissue distribution of basic drugs.

    Science.gov (United States)

    Assmus, Frauke; Houston, J Brian; Galetin, Aleksandra

    2017-11-15

    The prediction of tissue-to-plasma water partition coefficients (Kpu) from in vitro and in silico data using the tissue-composition based model (Rodgers & Rowland, J Pharm Sci. 2005, 94(6):1237-48.) is well established. However, distribution of basic drugs, in particular into lysosome-rich lung tissue, tends to be under-predicted by this approach. The aim of this study was to develop an extended mechanistic model for the prediction of Kpu which accounts for lysosomal sequestration and the contribution of different cell types in the tissue of interest. The extended model is based on compound-specific physicochemical properties and tissue composition data to describe drug ionization, distribution into tissue water and drug binding to neutral lipids, neutral phospholipids and acidic phospholipids in tissues, including lysosomes. Physiological data on the types of cells contributing to lung, kidney and liver, their lysosomal content and lysosomal pH were collated from the literature. The predictive power of the extended mechanistic model was evaluated using a dataset of 28 basic drugs (pK a ≥7.8, 17 β-blockers, 11 structurally diverse drugs) for which experimentally determined Kpu data in rat tissue have been reported. Accounting for the lysosomal sequestration in the extended mechanistic model improved the accuracy of Kpu predictions in lung compared to the original Rodgers model (56% drugs within 2-fold or 88% within 3-fold of observed values). Reduction in the extent of Kpu under-prediction was also evident in liver and kidney. However, consideration of lysosomal sequestration increased the occurrence of over-predictions, yielding overall comparable model performances for kidney and liver, with 68% and 54% of Kpu values within 2-fold error, respectively. High lysosomal concentration ratios relative to cytosol (>1000-fold) were predicted for the drugs investigated; the extent differed depending on the lysosomal pH and concentration of acidic phospholipids among

  5. The view from Kiev

    International Nuclear Information System (INIS)

    Kiselyov, S.

    1993-01-01

    This article reports the observations of correspondents for the Bulletin (two Russian journalists, one based in Moscow, the other in Kiev) who investigated the status of the Soviet Union's Black Sea Fleet and Ukraine's status as a non-nuclear-weapons state. After two years of wrangling and two earlier failed settlements, Russian President Boris Yeltsin met with Ukrainian President Leonid Kravchuk at Massandra in Crimea. On September 3, the leaders announced that Russia would buy out Ukraine's interest in the fleet and lease the port at Sevastopol. The Massandra summit was also supposed to settle Ukraine's status as a non-nuclear-weapons state. Described here are the Kiev-based correspondent's views on the Massandra summit (and its major topics), which was to have been called off by the Russian foreign ministry when Ukrainian Prime Minister Leonid Kuchma resigned

  6. Evaluation of current Louisiana flexible pavement structures using PMS data and new mechanistic-empirical pavement design guide : tech summary.

    Science.gov (United States)

    2012-04-01

    The new Mechanistic-Empirical Pavement Design Guide (MEPDG) developed under the National Cooperative Highway : Research Program (NCHRP) Project 1-37A represents a major change as compared to the 1993 AASHTO Pavement : Design Guide. MEPDG provides a r...

  7. Chirality-Controlled Growth of Single-Wall Carbon Nanotubes Using Vapor Phase Epitaxy: Mechanistic Understanding and Scalable Production

    Science.gov (United States)

    2016-09-15

    AFRL-AFOSR-VA-TR-2016-0319 Chirality-Controlled Growth of Single -Wall Carbon Nanotubes Using Vapor Phase Epitaxy: Mechanistic Understanding and...controlled growth of single -wall carbon nanotubes using vapor phase epitaxy: mechanistic understanding and scalable production FA9550-14-1-0115 Zhou...controlled synthesis of single -wall carbon nanotubes. Firstly, we have successfully demonstrated a vapor-phase-epitaxy-analogous general strategy for

  8. Mechanistic evaluation of Ginkgo biloba leaf extract-induced genotoxicity in L5178Y cells.

    Science.gov (United States)

    Lin, Haixia; Guo, Xiaoqing; Zhang, Suhui; Dial, Stacey L; Guo, Lei; Manjanatha, Mugimane G; Moore, Martha M; Mei, Nan

    2014-06-01

    Ginkgo biloba has been used for many thousand years as a traditional herbal remedy and its extract has been consumed for many decades as a dietary supplement. Ginkgo biloba leaf extract is a complex mixture with many constituents, including flavonol glycosides and terpene lactones. The National Toxicology Program 2-year cancer bioassay found that G. biloba leaf extract targets the liver, thyroid gland, and nose of rodents; however, the mechanism of G. biloba leaf extract-associated carcinogenicity remains unclear. In the current study, the in vitro genotoxicity of G. biloba leaf extract and its eight constituents was evaluated using the mouse lymphoma assay (MLA) and Comet assay. The underlying mechanisms of G. biloba leaf extract-associated genotoxicity were explored. Ginkgo biloba leaf extract, quercetin, and kaempferol resulted in a dose-dependent increase in the mutant frequency and DNA double-strand breaks (DSBs). Western blot analysis confirmed that G. biloba leaf extract, quercetin, and kaempferol activated the DNA damage signaling pathway with increased expression of γ-H2AX and phosphorylated Chk2 and Chk1. In addition, G. biloba leaf extract produced reactive oxygen species and decreased glutathione levels in L5178Y cells. Loss of heterozygosity analysis of mutants indicated that G. biloba leaf extract, quercetin, and kaempferol treatments resulted in extensive chromosomal damage. These results indicate that G. biloba leaf extract and its two constituents, quercetin and kaempferol, are mutagenic to the mouse L5178Y cells and induce DSBs. Quercetin and kaempferol likely are major contributors to G. biloba leaf extract-induced genotoxicity.

  9. Ways of Viewing Pictorial Plasticity.

    Science.gov (United States)

    Wijntjes, Maarten W A

    2017-01-01

    The plastic effect is historically used to denote various forms of stereopsis. The vivid impression of depth often associated with binocular stereopsis can also be achieved in other ways, for example, using a synopter. Accounts of this go back over a hundred years. These ways of viewing all aim to diminish sensorial evidence that the picture is physically flat. Although various viewing modes have been proposed in the literature, their effects have never been compared. In the current study, we compared three viewing modes: monocular blur, synoptic viewing, and free viewing (using a placebo synopter). By designing a physical embodiment that was indistinguishable for the three experimental conditions, we kept observers naïve with respect to the differences between them; 197 observers participated in an experiment where the three viewing modes were compared by performing a rating task. Results indicate that synoptic viewing causes the largest plastic effect. Monocular blur scores lower than synoptic viewing but is still rated significantly higher than the baseline conditions. The results strengthen the idea that synoptic viewing is not due to a placebo effect. Furthermore, monocular blur has been verified for the first time as a way of experiencing the plastic effect, although the effect is smaller than synoptic viewing. We discuss the results with respect to the theoretical basis for the plastic effect. We show that current theories are not described with sufficient details to explain the differences we found.

  10. Ways of Viewing Pictorial Plasticity

    Directory of Open Access Journals (Sweden)

    Maarten W. A. Wijntjes

    2017-03-01

    Full Text Available The plastic effect is historically used to denote various forms of stereopsis. The vivid impression of depth often associated with binocular stereopsis can also be achieved in other ways, for example, using a synopter. Accounts of this go back over a hundred years. These ways of viewing all aim to diminish sensorial evidence that the picture is physically flat. Although various viewing modes have been proposed in the literature, their effects have never been compared. In the current study, we compared three viewing modes: monocular blur, synoptic viewing, and free viewing (using a placebo synopter. By designing a physical embodiment that was indistinguishable for the three experimental conditions, we kept observers naïve with respect to the differences between them; 197 observers participated in an experiment where the three viewing modes were compared by performing a rating task. Results indicate that synoptic viewing causes the largest plastic effect. Monocular blur scores lower than synoptic viewing but is still rated significantly higher than the baseline conditions. The results strengthen the idea that synoptic viewing is not due to a placebo effect. Furthermore, monocular blur has been verified for the first time as a way of experiencing the plastic effect, although the effect is smaller than synoptic viewing. We discuss the results with respect to the theoretical basis for the plastic effect. We show that current theories are not described with sufficient details to explain the differences we found.

  11. Views from Space

    Science.gov (United States)

    Kitmacher, Gary H.

    2002-01-01

    aircraft like the high-flying U-2 spy planes for. Weather satellites permitted weather predictions as never before. Satellites were developed in the first ten years of the space program for earth resources and mapping. In this paper and presentation we will observe some of the best views taken in space and from space...of the Earth, and the moon and beyond. We will travel in space with our astronauts. Some of the photographs we will see are famous and others not nearly so. We will discuss some of the history behind the pictures and some of the benefits that have been gained from the views from space.

  12. Dutch radiodiagnostics viewed internationally

    International Nuclear Information System (INIS)

    Valois, J.C. de

    1990-01-01

    Dutch radiodiagnostics viewed internationally. - A quantitative description of diagnostic radiology is given in terms of radiological density (the number of radiological examinations per 1000 inhibitants), consumptions of roentgen film and contrast media. The data concerning examinations were recorded by a yearly inquiry system addressing all Dutch radiologists. The consumption of film and contrast media were derived from the data banks of the industries. In comparing these data with the data for Western Europe, Japan and the United States it is remarkable that diagnostic radiology scores lowest in regard to density, film consumption and use of contrast media. Only in the use of 35 mm cinefilm (coronary angiography) is The Netherlands number 2 on the list preceded by the United States. As a consequence radiation exposure of the population caused by diagnostic radiology is low in The Netherlands. Although the technical condition of the equipment is good due to regular and preventive service the life-span of the radiological equipment is gradually increasing beyond the limits of the normal economic depreciation. Growing arrears are found in the application of new technology: ultrasound, computer tomography and magnetic resonance imaging. The substitution of high osmolar contrast media by low osmolar media is also laggin gbehind. (author). 10 refs.; 1 fig.; 4 tab

  13. A journalist's view

    International Nuclear Information System (INIS)

    Coudret, Paul

    1989-01-01

    This paper is the result of five years of experience with the nuclear world in Switzerland (five Swiss nuclear plants) from the point of view of a journalist, who doesn't pretend to know everything; who is neither scientific nor a technical journalist, he is writing for the man in the street, and works for a daily paper i.e. has to work very fast and as close to the reality as possible. Understanding and mutual confidence between the nuclear industry and media is emphasised as essential. 'Nuclear' people are specialists and are warned about the fact that they are dealing with non-specialists, journalists and the public who would like to understand what are the processes that might affect them and do not have a dictionary of technical terminology at hand. It is pointed out that the nuclear industry should speak openly about problems and accept being criticised if they want to restore confidence with the media and with the public

  14. From ancient Greece to the cognitive revolution: A comprehensive view of physical rehabilitation sciences.

    Science.gov (United States)

    Martínez-Pernía, David; González-Castán, Óscar; Huepe, David

    2017-02-01

    The development of rehabilitation has traditionally focused on measurements of motor disorders and measurements of the improvements produced during the therapeutic process; however, physical rehabilitation sciences have not focused on understanding the philosophical and scientific principles in clinical intervention and how they are interrelated. The main aim of this paper is to explain the foundation stones of the disciplines of physical therapy, occupational therapy, and speech/language therapy in recovery from motor disorder. To reach our goals, the mechanistic view and how it is integrated into physical rehabilitation will first be explained. Next, a classification into mechanistic therapy based on an old version (automaton model) and a technological version (cyborg model) will be shown. Then, it will be shown how physical rehabilitation sciences found a new perspective in motor recovery, which is based on functionalism, during the cognitive revolution in the 1960s. Through this cognitive theory, physical rehabilitation incorporated into motor recovery of those therapeutic strategies that solicit the activation of the brain and/or symbolic processing; aspects that were not taken into account in mechanistic therapy. In addition, a classification into functionalist rehabilitation based on a computational therapy and a brain therapy will be shown. At the end of the article, the methodological principles in physical rehabilitation sciences will be explained. It will allow us to go deeper into the differences and similarities between therapeutic mechanism and therapeutic functionalism.

  15. Panorama completion for street views

    OpenAIRE

    Zhu, Zhe; Martin, Ralph Robert; Hu, Shi-Min

    2015-01-01

    This paper considers panorama images used for street views. Their viewing angle of 360° causes pixels at the top and bottom to appear stretched and warped. Although current image completion algorithms work well, they cannot be directly used in the presence of such distortions found in panoramas of street views. We thus propose a novel approach to complete such 360° panoramas using optimization-based projection to deal with distortions. Experimental results show that our approach is efficient ...

  16. Utilization of Mechanistic Enzymology to Evaluate the Significance of ADP Binding to Human Lon Protease

    Directory of Open Access Journals (Sweden)

    Jennifer Fishovitz

    2017-07-01

    Full Text Available Lon, also known as Protease La, is one of the simplest ATP-dependent proteases. It is a homooligomeric enzyme comprised of an ATPase domain and a proteolytic domain in each enzyme subunit. Despite sharing about 40% sequence identity, human and Escherichia coli Lon proteases utilize a highly conserved ATPase domain found in the AAA+ family to catalyze ATP hydrolysis, which is needed to activate protein degradation. In this study, we utilized mechanistic enzymology techniques to show that despite comparable kcat and Km parameters found in the ATPase activity, human and E. coli Lon exhibit significantly different susceptibility to ADP inhibition. Due to the low affinity of human Lon for ADP, the conformational changes in human Lon generated from the ATPase cycle are also different. The relatively low affinity of human Lon for ADP cannot be accounted for by reversibility in ATP hydrolysis, as a positional isotope exchange experiment demonstrated both E. coli Lon and human Lon catalyzed ATP hydrolysis irreversibly. A limited tryptic digestion study however indicated that human and E. coli Lon bind to ADP differently. Taken together, the findings reported in this research article suggest that human Lon is not regulated by a substrate-promoted ADP/ATP exchange mechanism as found in the bacterial enzyme homolog. The drastic difference in structural changes associated with ADP interaction with the two protease homologs offer potential for selective inhibitor design and development through targeting the ATPase sites. In addition to revealing unique mechanistic differences that distinguish human vs. bacterial Lon, this article underscores the benefit of mechanistic enzymology in deciphering the physiological mechanism of action of Lon proteases and perhaps other closely related ATP-dependent proteases in the future.

  17. A metabonomic approach for mechanistic exploration of pre-clinical toxicology.

    Science.gov (United States)

    Coen, Muireann

    2010-12-30

    Metabonomics involves the application of advanced analytical tools to profile the diverse metabolic complement of a given biofluid or tissue. Subsequent statistical modelling of the complex multivariate spectral profiles enables discrimination between phenotypes of interest and identifies panels of discriminatory metabolites that represent candidate biomarkers. This review article presents an overview of recent developments in the field of metabonomics with a focus on application to pre-clinical toxicology studies. Recent research investigations carried out as part of the international COMET 2 consortium project on the hepatotoxic action of the aminosugar, galactosamine (galN) are presented. The application of advanced, high-field NMR spectroscopy is demonstrated, together with complementary application of a targeted mass spectrometry platform coupled with ultra-performance liquid chromatography. Much novel mechanistic information has been gleaned on both the mechanism of galN hepatotoxicity in multiple biofluids and tissues, and on the protection afforded by co-administration of glycine and uridine. The simultaneous identification of both the metabolic fate of galN and its associated endogenous consequences in spectral profiles is demonstrated. Furthermore, metabonomic assessment of inter-animal variability in response to galN presents enhanced mechanistic insight on variable response phentoypes and is relevant to understanding wider aspects of individual variability in drug response. This exemplar highlights the analytical and statistical tools commonly applied in metabonomic studies and notably, the approach is applicable to the study of any toxin/drug or intervention of interest. The metabonomic approach holds considerable promise and potential to significantly advance our understanding of the mechanistic bases for adverse drug reactions. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  18. Mechanistic Pathways of Mindfulness Meditation in Combat Veterans With Posttraumatic Stress Disorder.

    Science.gov (United States)

    Wahbeh, Helané; Goodrich, Elena; Goy, Elizabeth; Oken, Barry S

    2016-04-01

    This study's objective was to evaluate the effect of two common components of meditation (mindfulness and slow breathing) on potential mechanistic pathways. A total of 102 combat veterans with posttraumatic stress disorder (PTSD) were randomized to (a) the body scan mindfulness meditation (MM), (b) slow breathing (SB) with a biofeedback device, (c) mindful awareness of the breath with an intention to slow the breath (MM+SB), or (d) sitting quietly (SQ). Participants had 6 weekly one-on-one sessions with 20 minutes of daily home practice. The mechanistic pathways and measures were as follows: (a) autonomic nervous system (hyperarousal symptoms, heart rate [HR], and heart rate variability [HRV]); (b) frontal cortex activity (attentional network task [ANT] conflict effect and event-related negativity and intrusive thoughts); and (c) hypothalamic-pituitary-adrenal axis (awakening cortisol). PTSD measures were also evaluated. Meditation participants had significant but modest within-group improvement in PTSD and related symptoms, although there were no effects between groups. Perceived impression of PTSD symptom improvement was greater in the meditation arms compared with controls. Resting respiration decreased in the meditation arms compared with SQ. For the mechanistic pathways, (a) subjective hyperarousal symptoms improved within-group (but not between groups) for MM, MM+SB, and SQ, while HR and HRV did not; (b) intrusive thoughts decreased in MM compared with MM+SB and SB, while the ANT measures did not change; and (c) MM had lower awakening cortisol within-group (but not between groups). Treatment effects were mostly specific to self-report rather than physiological measures. Continued research is needed to further evaluate mindfulness meditation's mechanism in people with PTSD. © 2016 Wiley Periodicals, Inc.

  19. ReactionPredictor: prediction of complex chemical reactions at the mechanistic level using machine learning.

    Science.gov (United States)

    Kayala, Matthew A; Baldi, Pierre

    2012-10-22

    Proposing reasonable mechanisms and predicting the course of chemical reactions is important to the practice of organic chemistry. Approaches to reaction prediction have historically used obfuscating representations and manually encoded patterns or rules. Here we present ReactionPredictor, a machine learning approach to reaction prediction that models elementary, mechanistic reactions as interactions between approximate molecular orbitals (MOs). A training data set of productive reactions known to occur at reasonable rates and yields and verified by inclusion in the literature or textbooks is derived from an existing rule-based system and expanded upon with manual curation from graduate level textbooks. Using this training data set of complex polar, hypervalent, radical, and pericyclic reactions, a two-stage machine learning prediction framework is trained and validated. In the first stage, filtering models trained at the level of individual MOs are used to reduce the space of possible reactions to consider. In the second stage, ranking models over the filtered space of possible reactions are used to order the reactions such that the productive reactions are the top ranked. The resulting model, ReactionPredictor, perfectly ranks polar reactions 78.1% of the time and recovers all productive reactions 95.7% of the time when allowing for small numbers of errors. Pericyclic and radical reactions are perfectly ranked 85.8% and 77.0% of the time, respectively, rising to >93% recovery for both reaction types with a small number of allowed errors. Decisions about which of the polar, pericyclic, or radical reaction type ranking models to use can be made with >99% accuracy. Finally, for multistep reaction pathways, we implement the first mechanistic pathway predictor using constrained tree-search to discover a set of reasonable mechanistic steps from given reactants to given products. Webserver implementations of both the single step and pathway versions of Reaction

  20. Mechanistic Simmer-3 analyses of severe transients in accelerator driven systems (Ads)

    Energy Technology Data Exchange (ETDEWEB)

    Morita, K.; Rineiski, A.; Kiefhaber, E.; Maschek, W.; Flad, M. [Forschungszentrum Karlsruhe, Institute for Nuclear and Energy Technology, Karlsruhe (Germany); Rimpault, G. [CEA Cadarache, 13 - Saint Paul lez Durance (France); Coste, P.; Pigny, S. [CEA Grenoble, 38 (France); Kondo, S.; Tobita, Y.; Fujita, S. [Japan Nuclear Cycle Development Institute, O-arai, Ibaraki (Japan)

    2001-07-01

    Mechanistic analyses have been performed for various potential transients and accident initiators in subcritical accelerator driven systems (ADS) using the reactor safety analysis code SIMMER-III extended to describe ADS specifics. The current analyses aim at a deeper understanding of the severe accident behavior of an ADS dedicated to incinerate nuclear waste. The dedicated ADS with pure plutonium and minor actinide fuel without fertile is compared to an ADS of the energy amplifier type with thorium fuel. Results of the present analyses demonstrate that for such a dedicated ADS safety problems might exist. They are related to the inherent reactivity potentials and deteriorated safety parameters in such cores. (author)

  1. Development of a mechanistically based computer simulation of nitrogen oxide absorption in packed towers

    International Nuclear Information System (INIS)

    Counce, R.M.

    1981-01-01

    A computer simulation for nitrogen oxide (NO/sub x/) scrubbing in packed towers was developed for use in process design and process control. This simulation implements a mechanistically based mathematical model, which was formulated from (1) an exhaustive literature review; (2) previous NO/sub x/ scrubbing experience with sieve-plate towers; and (3) comparisons of sequential sets of experiments. Nitrogen oxide scrubbing is characterized by simultaneous absorption and desorption phenomena: the model development is based on experiments designed to feature these two phenomena. The model was then successfully tested in experiments designed to put it in jeopardy

  2. Mechanistic modeling of reactive soil nitrogen emissions across agricultural management practices

    Science.gov (United States)

    Rasool, Q. Z.; Miller, D. J.; Bash, J. O.; Venterea, R. T.; Cooter, E. J.; Hastings, M. G.; Cohan, D. S.

    2017-12-01

    The global reactive nitrogen (N) budget has increased by a factor of 2-3 from pre-industrial levels. This increase is especially pronounced in highly N fertilized agricultural regions in summer. The reactive N emissions from soil to atmosphere can be in reduced (NH3) or oxidized (NO, HONO, N2O) forms, depending on complex biogeochemical transformations of soil N reservoirs. Air quality models like CMAQ typically neglect soil emissions of HONO and N2O. Previously, soil NO emissions estimated by models like CMAQ remained parametric and inconsistent with soil NH3 emissions. Thus, there is a need to more mechanistically and consistently represent the soil N processes that lead to reactive N emissions to the atmosphere. Our updated approach estimates soil NO, HONO and N2O emissions by incorporating detailed agricultural fertilizer inputs from EPIC, and CMAQ-modeled N deposition, into the soil N pool. EPIC addresses the nitrification, denitrification and volatilization rates along with soil N pools for agricultural soils. Suitable updates to account for factors like nitrite (NO2-) accumulation not addressed in EPIC, will also be made. The NO and N2O emissions from nitrification and denitrification are computed mechanistically using the N sub-model of DAYCENT. These mechanistic definitions use soil water content, temperature, NH4+ and NO3- concentrations, gas diffusivity and labile C availability as dependent parameters at various soil layers. Soil HONO emissions found to be most probable under high NO2- availability will be based on observed ratios of HONO to NO emissions under different soil moistures, pH and soil types. The updated scheme will utilize field-specific soil properties and N inputs across differing manure management practices such as tillage. Comparison of the modeled soil NO emission rates from the new mechanistic and existing schemes against field measurements will be discussed. Our updated framework will help to predict the diurnal and daily variability

  3. A comprehensive mechanistic model for simulating algal growth dynamics in photobioreactors.

    Science.gov (United States)

    Shriwastav, Amritanshu; Thomas, Jeenu; Bose, Purnendu

    2017-06-01

    A comprehensive mechanistic model for describing algal growth dynamics in a photobioreactor was developed in this work with state of the art understanding and realistic assumptions for major associated processes. The model included 27 state variables related to various algal processes. This model was validated with extensive experimental data obtained from independent growth experiments in batch reactors, and was able to simulate system performance reasonably well. The comprehensive nature of the formulation also highlights the complex inter-relationship between all processes, and provides a tool for gaining more systematic insights into algal behavior in photobioreactors and other such systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Comparison of mechanistic models in the initial rate enzymatic hydrolysis of AFEX-treated wheat straw

    Directory of Open Access Journals (Sweden)

    Agbogbo Frank K

    2010-03-01

    Full Text Available Abstract Background Different mechanistic models have been used in the literature to describe the enzymatic hydrolysis of pretreated biomass. Although these different models have been applied to different substrates, most of these mechanistic models fit into two- and three-parameter mechanistic models. The purpose of this study is to compare the models and determine the activation energy and the enthalpy of adsorption of Trichoderma reesei enzymes on ammonia fibre explosion (AFEX-treated wheat straw. Experimental enzymatic hydrolysis data from AFEX-treated wheat straw were modelled with two- and three-parameter mechanistic models from the literature. In order to discriminate between the models, initial rate data at 49°C were subjected to statistical analysis (analysis of variance and scatter plots. Results For three-parameter models, the HCH-1 model best fitted the experimental data; for two-parameter models Michaelis-Menten (M-M best fitted the experimental data. All the three-parameter models fitted the data better than the two-parameter models. The best three models at 49°C (HCH-1, Huang and M-M were compared using initial rate data at three temperatures (35°, 42° and 49°C. The HCH-1 model provided the best fit based on the F values, the scatter plot and the residual sum of squares. Also, its kinetic parameters were linear in Arrhenius/van't Hoff's plots, unlike the other models. The activation energy (Ea is 47.6 kJ/mol and the enthalpy change of adsorption (ΔH is -118 kJ/mol for T. reesei enzymes on AFEX-treated wheat straw. Conclusion Among the two-parameter models, Michaelis-Menten model provided the best fit compared to models proposed by Humphrey and Wald. For the three-parameter models, HCH-1 provided the best fit because the model includes a fractional coverage parameter (ϕ which accounts for the number of reactive sites covered by the enzymes.

  5. Mechanistic Investigations of the Iron(III)-Catalyzed Carbonyl-Olefin Metathesis Reaction.

    Science.gov (United States)

    Ludwig, Jacob R; Phan, Susan; McAtee, Christopher C; Zimmerman, Paul M; Devery, James J; Schindler, Corinna S

    2017-08-09

    Iron(III)-catalyzed carbonyl-olefin ring-closing metathesis represents a new approach toward the assembly of molecules traditionally generated by olefin-olefin metathesis or olefination. Herein, we report detailed synthetic, spectroscopic, kinetic, and computational studies to determine the mechanistic features imparted by iron(III), substrate, and temperature to the catalytic cycle. These data are consistent with an iron(III)-mediated asynchronous, concerted [2+2]-cycloaddition to form an intermediate oxetane as the turnover-limiting step. Fragmentation of the oxetane via Lewis acid-activation results in the formation of five- and six-membered unsaturated carbocycles.

  6. Mechanistic phenotypes: an aggregative phenotyping strategy to identify disease mechanisms using GWAS data.

    Directory of Open Access Journals (Sweden)

    Jonathan D Mosley

    Full Text Available A single mutation can alter cellular and global homeostatic mechanisms and give rise to multiple clinical diseases. We hypothesized that these disease mechanisms could be identified using low minor allele frequency (MAF<0.1 non-synonymous SNPs (nsSNPs associated with "mechanistic phenotypes", comprised of collections of related diagnoses. We studied two mechanistic phenotypes: (1 thrombosis, evaluated in a population of 1,655 African Americans; and (2 four groupings of cancer diagnoses, evaluated in 3,009 white European Americans. We tested associations between nsSNPs represented on GWAS platforms and mechanistic phenotypes ascertained from electronic medical records (EMRs, and sought enrichment in functional ontologies across the top-ranked associations. We used a two-step analytic approach whereby nsSNPs were first sorted by the strength of their association with a phenotype. We tested associations using two reverse genetic models and standard additive and recessive models. In the second step, we employed a hypothesis-free ontological enrichment analysis using the sorted nsSNPs to identify functional mechanisms underlying the diagnoses comprising the mechanistic phenotypes. The thrombosis phenotype was solely associated with ontologies related to blood coagulation (Fisher's p = 0.0001, FDR p = 0.03, driven by the F5, P2RY12 and F2RL2 genes. For the cancer phenotypes, the reverse genetics models were enriched in DNA repair functions (p = 2×10-5, FDR p = 0.03 (POLG/FANCI, SLX4/FANCP, XRCC1, BRCA1, FANCA, CHD1L while the additive model showed enrichment related to chromatid segregation (p = 4×10-6, FDR p = 0.005 (KIF25, PINX1. We were able to replicate nsSNP associations for POLG/FANCI, BRCA1, FANCA and CHD1L in independent data sets. Mechanism-oriented phenotyping using collections of EMR-derived diagnoses can elucidate fundamental disease mechanisms.

  7. Mechanistic Simmer-3 analyses of severe transients in accelerator driven systems (Ads)

    International Nuclear Information System (INIS)

    Morita, K.; Rineiski, A.; Kiefhaber, E.; Maschek, W.; Flad, M.; Rimpault, G.; Coste, P.; Pigny, S.; Kondo, S.; Tobita, Y.; Fujita, S.

    2001-01-01

    Mechanistic analyses have been performed for various potential transients and accident initiators in subcritical accelerator driven systems (ADS) using the reactor safety analysis code SIMMER-III extended to describe ADS specifics. The current analyses aim at a deeper understanding of the severe accident behavior of an ADS dedicated to incinerate nuclear waste. The dedicated ADS with pure plutonium and minor actinide fuel without fertile is compared to an ADS of the energy amplifier type with thorium fuel. Results of the present analyses demonstrate that for such a dedicated ADS safety problems might exist. They are related to the inherent reactivity potentials and deteriorated safety parameters in such cores. (author)

  8. Ruthenium-Catalyzed Transformations of Alcohols: Mechanistic Investigations and Methodology Development

    DEFF Research Database (Denmark)

    Makarov, Ilya; Madsen, Robert; Fristrup, Peter

    unknown ruthenium-catalyzed dehydrogenative Guerbet reaction with secondary alcohols to give ketones was discovered. The reaction conditions were optimized and the scope and the limitations were studied. It was found that only acyclic 2-methyl carbinols and simple cyclic alcohols underwent...... with dimethoxyisopropylidene and pyridilidene ligands could be more active than RuCl2(IiPr)(p-cymene) used in the mechanistic investigation. Two analogs of the calculated complexes were synthesized but were not isolated in a pure form. The amidation reaction catalyzed by a mixture containing the N-ethyl pyridilidene...

  9. Bird Migration Under Climate Change - A Mechanistic Approach Using Remote Sensing

    Science.gov (United States)

    Smith, James A.; Blattner, Tim; Messmer, Peter

    2010-01-01

    The broad-scale reductions and shifts that may be expected under climate change in the availability and quality of stopover habitat for long-distance migrants is an area of increasing concern for conservation biologists. Researchers generally have taken two broad approaches to the modeling of migration behaviour to understand the impact of these changes on migratory bird populations. These include models based on causal processes and their response to environmental stimulation, "mechanistic models", or models that primarily are based on observed animal distribution patterns and the correlation of these patterns with environmental variables, i.e. "data driven" models. Investigators have applied the latter technique to forecast changes in migration patterns with changes in the environment, for example, as might be expected under climate change, by forecasting how the underlying environmental data layers upon which the relationships are built will change over time. The learned geostatstical correlations are then applied to the modified data layers.. However, this is problematic. Even if the projections of how the underlying data layers will change are correct, it is not evident that the statistical relationships will remain the same, i.e. that the animal organism may not adapt its' behaviour to the changing conditions. Mechanistic models that explicitly take into account the physical, biological, and behaviour responses of an organism as well as the underlying changes in the landscape offer an alternative to address these shortcomings. The availability of satellite remote sensing observations at multiple spatial and temporal scales, coupled with advances in climate modeling and information technologies enable the application of the mechanistic models to predict how continental bird migration patterns may change in response to environmental change. In earlier work, we simulated the impact of effects of wetland loss and inter-annual variability on the fitness of

  10. Impacts of wildlife viewing at Dixville Notch Wildlife Viewing Area

    Science.gov (United States)

    Judith K. Silverberg; Peter J. Pekins; Robert A. Robertson

    2002-01-01

    Dixville Notch Wildlife Viewing Area provided an opportunity to examine the motivations, knowledge level and attitudes of wildlife viewers as well as the response of wildlife to observation and other human caused stimuli at a designated wildlife viewing site. Using integrated social science and biological information allowed recommendations to be made for managing...

  11. Does laryngoscopic view after intubation predict laryngoscopic view before intubation?

    Science.gov (United States)

    Foglia, Julena; Archer, David; Pytka, Saul; Baghirzada, Leyla; Duttchen, Kaylene

    2016-09-01

    To determine if an endotracheal (ET) tube will distort the laryngeal view obtained with direct laryngoscopy measuring with the modified Cormack-Lehane scale (MCL). Observational single-arm study. The University of Calgary teaching hospitals. Patients between 18 and 86 years of age undergoing elective surgical procedures. A total of 173 patients were enrolled and analyzed. Direct laryngoscopy view obtained before ET intubation and directly after intubation. The MCL scales were described for each view obtained and compared to each other with each patient serving as their own control. The primary objective was a change in the best obtainable view by direct laryngoscopy from an acceptable view (MCLS 1 or 2a) to an unacceptable view (MCLS 2b, 3, or 4) or changing from an unacceptable view (MCLS 2b, 3, or 4) to an acceptable view (MCLS 1 or 2a). The main finding of this study was that the ET tube altered the MCL in 58 (33%) of 173 patients, "worsening" the grade in 30 patients (17.34%) and "improving" the grade in 28 patients (16.18%). We performed a prospective observational study to address the predictive value of postintubation laryngoscopy grade in adults. The presence of the ET tube both increased visualization of the glottis and worsened the view in different subjects. The important outcome was that the presence of the ET tube did in fact change the view obtained of the larynx during direct laryngoscopy. In conclusion, postintubation MCL grades may not be reliable to predict laryngeal grade and should be used with caution in the right clinical context. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Trichome isolation with and without fixation using laser microdissection and pressure catapulting followed by RNA amplification: expression of genes of terpene metabolism in apical and sub-apical trichome cells of Artemisia annua L.

    Science.gov (United States)

    Olofsson, Linda; Lundgren, Anneli; Brodelius, Peter E

    2012-02-01

    The aim of this project was to evaluate the effect of fixation on plant material prior to Laser Microdissection and Pressure Catapulting (LMPC) and to identify an appropriate method for preserving good RNA quality after cell isolation. Therefore, flower buds from Artemisia annua L. were exposed to either the fixative formaldehyde or a non-fixative buffer prior to cell isolation by LMPC. Proteinase K was used after cell isolation from fixed plant tissue, in an attempt to improve the RNA yield. The ability to detect gene expression using real-time quantitative PCR with or without previous amplification of RNA from cells isolated by LMPC was also evaluated. Conclusively, we describe a new technique, without fixation, enabling complete isolation of intact glandular secretory trichomes and specific single trichome cells of A. annua. This method is based on LMPC and preserves good RNA quality for subsequent RNA expression studies of both whole trichomes, apical and sub-apical cells from trichomes of A. annua. Using this method, expression of genes of terpene metabolism was studied by real-time quantitative PCR. Expression of genes involved in artemisinin biosynthesis was observed in both apical and sub-apical cells. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  13. Simultaneous Quantification of Flavonol Glycosides, Terpene Lactones, Biflavones, Proanthocyanidins, and Ginkgolic Acids in Ginkgo biloba Leaves from Fruit Cultivars by Ultrahigh-Performance Liquid Chromatography Coupled with Triple Quadrupole Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Xin Yao

    2013-01-01

    Full Text Available On the basis of liquid chromatography coupled with triple quadrupole mass spectrometry working in multiple reaction monitoring mode, an analytical method has been established to simultaneously determine flavonol glycosides, terpene lactones, biflavones, proanthocyanidins, and ginkgolic acids in Ginkgo biloba leaves. Chromatographic separation was carried out on an Acquity BEH C18 column (100 mm × 2.1 mm, 1.7 μm with gradient elution of acetonitrile and 0.10% formic acid (v/v at a flow rate of 0.4 mL/min, and column temperature 30°C. The developed method was validated in terms of linearity, accuracy, precision, stability, and sensitivity. The optimized method was successfully applied to analyze twenty-two G. biloba leaf samples of fruit cultivars collected from different places in China. Furthermore, hierarchical clustering analysis (HCA was performed to evaluate and classify the samples according to the contents of the twenty-four chemical constituents. All of the results demonstrated that the developed method was useful for the overall evaluation of the quality of G. biloba leaves, and this study was also helpful for the comprehensive utilization and development of G. biloba resources.

  14. Global Profiling and Novel Structure Discovery Using Multiple Neutral Loss/Precursor Ion Scanning Combined with Substructure Recognition and Statistical Analysis (MNPSS): Characterization of Terpene-Conjugated Curcuminoids in Curcuma longa as a Case Study.

    Science.gov (United States)

    Qiao, Xue; Lin, Xiong-hao; Ji, Shuai; Zhang, Zheng-xiang; Bo, Tao; Guo, De-an; Ye, Min

    2016-01-05

    To fully understand the chemical diversity of an herbal medicine is challenging. In this work, we describe a new approach to globally profile and discover novel compounds from an herbal extract using multiple neutral loss/precursor ion scanning combined with substructure recognition and statistical analysis. Turmeric (the rhizomes of Curcuma longa L.) was used as an example. This approach consists of three steps: (i) multiple neutral loss/precursor ion scanning to obtain substructure information; (ii) targeted identification of new compounds by extracted ion current and substructure recognition; and (iii) untargeted identification using total ion current and multivariate statistical analysis to discover novel structures. Using this approach, 846 terpecurcumins (terpene-conjugated curcuminoids) were discovered from turmeric, including a number of potentially novel compounds. Furthermore, two unprecedented compounds (terpecurcumins X and Y) were purified, and their structures were identified by NMR spectroscopy. This study extended the application of mass spectrometry to global profiling of natural products in herbal medicines and could help chemists to rapidly discover novel compounds from a complex matrix.

  15. Methodology for the identification of tri-terpenes mixtures components by {sup 13} C NMR; Metodologia para identificao dos componentes de misturas de triterpenos por RMN de {sup 13} C

    Energy Technology Data Exchange (ETDEWEB)

    Olea, Roberto S.G.

    1990-12-31

    This work describes a methodology for the identification of tri terpenes complex mixtures by {sup 13} C NMR. The use of {sup 13} C NMR techniques, such as obtention of noise decoupled spectra, DEPT 135 and DEPT 90 sequences, allowed the identification of components of triterpene mixtures with identical functionality through comparison of observed {sup 13} C NMR chemical shifts with {sup 13} C NMR chemical shifts reported in the literature. The method proved to be specially helpful in the identification of triterpenes by analysis of chemical shifts assignable to doubly bonded carbons, since the particular position of such double bonds is characteristic of some triterpene skeletons. Application of this methodology indicated the presence of bauerenol, {alpha}-amyrin and {beta}-amyrin in Acmanthera latifolis Griseb. (Malpighiaceae); of germanicone, lupenone, {alpha}-amyrenone and {beta}-amyrenone in Alibertia macrophylla A. Rich. (Rubiaceae); of {alpha}-amyrin acetate, lupeol acetate and {beta}-amyrin acetate in Vernonia polyanthes Schreb. (Asteraceae); {alpha}-amyrenone, {beta}-amyrenone, boehmerone, friedelin, lupenone, {alpha}-amyrin, {beta}-amyrin and glutinol in Scoparia dulcis L. (Scrophulariaceae). (author). 37 refs., 93 figs.

  16. Communications and Development: Two Views.

    Science.gov (United States)

    Development Communication Report, 1977

    1977-01-01

    Two views on current international communication are presented--that of an American academician, and that of an Indian journalist. John Lent traces the rise of development journalism and development communication from the point of view of those who believe that individual freedom of expression should be treated as an inviolable right. Narinder…

  17. Wildlands management for wildlife viewing

    Science.gov (United States)

    Tamsie Cooper; William W. Shaw

    1979-01-01

    Wildlife in general and wildlife viewing in particular play significant roles in enriching the aesthetic experiences of visitors to wildlands. Effective management of wildlife for viewing must be based on human as well as biological information. The integration of the principles and techniques developed for game management with information on the human dimensions of...

  18. Behavioural View of Language Acquisition

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 13; Issue 5. Behavioural View of Language Acquisition. Rajeev Sangal. Book Review Volume 13 Issue 5 May 2008 pp 487-489. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/013/05/0487-0489 ...

  19. Television viewing and childhood obesity.

    Science.gov (United States)

    Robinson, T N

    2001-08-01

    Children spend a substantial portion of their lives watching television. Investigators have hypothesized that television viewing causes obesity by one or more of three mechanisms: (1) displacement of physical activity, (2) increased calorie consumption while watching or caused by the effects of advertising, and (3) reduced resting metabolism. The relationship between television viewing and obesity has been examined in a relatively large number of cross-sectional epidemiologic studies but few longitudinal studies. Many of these studies have found relatively weak, positive associations, but others have found no associations or mixed results; however, the weak and variable associations found in these studies may be the result of limitations in measurement. Several experimental studies of reducing television viewing recently have been completed. Most of these studies have not tested directly the effects of reducing television viewing behaviors alone, but their results support the suggestion that reducing television viewing may help to reduce the risk for obesity or help promote weight loss in obese children. Finally, one school-based, experimental study was designed specifically to test directly the causal relationship between television viewing behaviors and body fatness. The results of this randomized, controlled trial provide evidence that television viewing is a cause of increased body fatness and that reducing television viewing is a promising strategy for preventing childhood obesity.

  20. Detecting the impact of temperature on transmission of Zika, dengue, and chikungunya using mechanistic models.

    Science.gov (United States)

    Mordecai, Erin A; Cohen, Jeremy M; Evans, Michelle V; Gudapati, Prithvi; Johnson, Leah R; Lippi, Catherine A; Miazgowicz, Kerri; Murdock, Courtney C; Rohr, Jason R; Ryan, Sadie J; Savage, Van; Shocket, Marta S; Stewart Ibarra, Anna; Thomas, Matthew B; Weikel, Daniel P

    2017-04-01

    Recent epidemics of Zika, dengue, and chikungunya have heightened the need to understand the seasonal and geographic range of transmission by Aedes aegypti and Ae. albopictus mosquitoes. We use mechanistic transmission models to derive predictions for how the probability and magnitude of transmission for Zika, chikungunya, and dengue change with mean temperature, and we show that these predictions are well matched by human case data. Across all three viruses, models and human case data both show that transmission occurs between 18-34°C with maximal transmission occurring in a range from 26-29°C. Controlling for population size and two socioeconomic factors, temperature-dependent transmission based on our mechanistic model is an important predictor of human transmission occurrence and incidence. Risk maps indicate that tropical and subtropical regions are suitable for extended seasonal or year-round transmission, but transmission in temperate areas is limited to at most three months per year even if vectors are present. Such brief transmission windows limit the likelihood of major epidemics following disease introduction in temperate zones.

  1. Detecting the impact of temperature on transmission of Zika, dengue, and chikungunya using mechanistic models.

    Directory of Open Access Journals (Sweden)

    Erin A Mordecai

    2017-04-01

    Full Text Available Recent epidemics of Zika, dengue, and chikungunya have heightened the need to understand the seasonal and geographic range of transmission by Aedes aegypti and Ae. albopictus mosquitoes. We use mechanistic transmission models to derive predictions for how the probability and magnitude of transmission for Zika, chikungunya, and dengue change with mean temperature, and we show that these predictions are well matched by human case data. Across all three viruses, models and human case data both show that transmission occurs between 18-34°C with maximal transmission occurring in a range from 26-29°C. Controlling for population size and two socioeconomic factors, temperature-dependent transmission based on our mechanistic model is an important predictor of human transmission occurrence and incidence. Risk maps indicate that tropical and subtropical regions are suitable for extended seasonal or year-round transmission, but transmission in temperate areas is limited to at most three months per year even if vectors are present. Such brief transmission windows limit the likelihood of major epidemics following disease introduction in temperate zones.

  2. Ecological Forecasting in Chesapeake Bay: Using a Mechanistic-Empirical Modelling Approach

    Energy Technology Data Exchange (ETDEWEB)

    Brown, C. W.; Hood, Raleigh R.; Long, Wen; Jacobs, John M.; Ramers, D. L.; Wazniak, C.; Wiggert, J. D.; Wood, R.; Xu, J.

    2013-09-01

    The Chesapeake Bay Ecological Prediction System (CBEPS) automatically generates daily nowcasts and three-day forecasts of several environmental variables, such as sea-surface temperature and salinity, the concentrations of chlorophyll, nitrate, and dissolved oxygen, and the likelihood of encountering several noxious species, including harmful algal blooms and water-borne pathogens, for the purpose of monitoring the Bay's ecosystem. While the physical and biogeochemical variables are forecast mechanistically using the Regional Ocean Modeling System configured for the Chesapeake Bay, the species predictions are generated using a novel mechanistic empirical approach, whereby real-time output from the coupled physical biogeochemical model drives multivariate empirical habitat models of the target species. The predictions, in the form of digital images, are available via the World Wide Web to interested groups to guide recreational, management, and research activities. Though full validation of the integrated forecasts for all species is still a work in progress, we argue that the mechanistic–empirical approach can be used to generate a wide variety of short-term ecological forecasts, and that it can be applied in any marine system where sufficient data exist to develop empirical habitat models. This paper provides an overview of this system, its predictions, and the approach taken.

  3. Simulating the Risk of Liver Fluke Infection using a Mechanistic Hydro-epidemiological Model

    Science.gov (United States)

    Beltrame, Ludovica; Dunne, Toby; Rose, Hannah; Walker, Josephine; Morgan, Eric; Vickerman, Peter; Wagener, Thorsten

    2016-04-01

    Liver Fluke (Fasciola hepatica) is a common parasite found in livestock and responsible for considerable economic losses throughout the world. Risk of infection is strongly influenced by climatic and hydrological conditions, which characterise the host environment for parasite development and transmission. Despite on-going control efforts, increases in fluke outbreaks have been reported in recent years in the UK, and have been often attributed to climate change. Currently used fluke risk models are based on empirical relationships derived between historical climate and incidence data. However, hydro-climate conditions are becoming increasingly non-stationary due to climate change and direct anthropogenic impacts such as land use change, making empirical models unsuitable for simulating future risk. In this study we introduce a mechanistic hydro-epidemiological model for Liver Fluke, which explicitly simulates habitat suitability for disease development in space and time, representing the parasite life cycle in connection with key environmental conditions. The model is used to assess patterns of Liver Fluke risk for two catchments in the UK under current and potential future climate conditions. Comparisons are made with a widely used empirical model employing different datasets, including data from regional veterinary laboratories. Results suggest that mechanistic models can achieve adequate predictive ability and support adaptive fluke control strategies under climate change scenarios.

  4. Evolutionary and mechanistic drivers of laterality: A review and new synthesis.

    Science.gov (United States)

    Wiper, Mallory L

    2017-11-01

    Laterality, best understood as asymmetries of bilateral structures or biases in behaviour, has been demonstrated in species from all major vertebrate classes, and in many invertebrates, showing a large degree of evolutionary conservation across vertebrate groups. Despite the establishment of this phenomenon in so many species, however, the evolutionary and mechanistic study of laterality is uneven with numerous areas in this field requiring greater attention. Here, I present a partial review of how far the study of laterality has come, outlining previous pioneering work, I discuss the hypothesized costs and benefits of a lateralized brain and the suggested path of the evolution of laterality for populations and individuals. I propose an expansion of laterality research into areas that have been touched upon in the past but require stronger evidence from which the field will greatly benefit. Namely, I suggest a continuation of the phylogenetic approach to investigating laterality to better understand its evolutionary path; and a further focus on mechanistic drivers, with special attention to genetic and environmental effects. Putting together the puzzle of laterality using as many pieces as possible will provide a stronger understanding of this field, allowing us to continue to expand the field in novel ways.

  5. Non-destructive estimation of root pressure using sap flow, stem diameter measurements and mechanistic modelling.

    Science.gov (United States)

    De Swaef, Tom; Hanssens, Jochen; Cornelis, Annelies; Steppe, Kathy

    2013-02-01

    Upward water movement in plants via the xylem is generally attributed to the cohesion-tension theory, as a response to transpiration. Under certain environmental conditions, root pressure can also contribute to upward xylem water flow. Although the occurrence of root pressure is widely recognized, ambiguity exists about the exact mechanism behind root pressure, the main influencing factors and the consequences of root pressure. In horticultural crops, such as tomato (Solanum lycopersicum), root pressure is thought to cause cells to burst, and to have an important impact on the marketable yield. Despite the challenges of root pressure research, progress in this area is limited, probably because of difficulties with direct measurement of root pressure, prompting the need for indirect and non-destructive measurement techniques. A new approach to allow non-destructive and non-invasive estimation of root pressure is presented, using continuous measurements of sap flow and stem diameter variation in tomato combined with a mechanistic flow and storage model, based on cohesion-tension principles. Transpiration-driven sap flow rates are typically inversely related to stem diameter changes; however, this inverse relationship was no longer valid under conditions of low transpiration. This decoupling between sap flow rates and stem diameter variations was mathematically related to root pressure. Root pressure can be estimated in a non-destructive, repeatable manner, using only external plant sensors and a mechanistic model.

  6. Life at the Common Denominator: Mechanistic and Quantitative Biology for the Earth and Space Sciences

    Science.gov (United States)

    Hoehler, Tori M.

    2010-01-01

    The remarkable challenges and possibilities of the coming few decades will compel the biogeochemical and astrobiological sciences to characterize the interactions between biology and its environment in a fundamental, mechanistic, and quantitative fashion. The clear need for integrative and scalable biology-environment models is exemplified in the Earth sciences by the challenge of effectively addressing anthropogenic global change, and in the space sciences by the challenge of mounting a well-constrained yet sufficiently adaptive and inclusive search for life beyond Earth. Our understanding of the life-planet interaction is still, however, largely empirical. A variety of approaches seek to move from empirical to mechanistic descriptions. One approach focuses on the relationship between biology and energy, which is at once universal (all life requires energy), unique (life manages energy flow in a fashion not seen in abiotic systems), and amenable to characterization and quantification in thermodynamic terms. Simultaneously, a focus on energy flow addresses a critical point of interface between life and its geological, chemical, and physical environment. Characterizing and quantifying this relationship for life on Earth will support the development of integrative and predictive models for biology-environment dynamics. Understanding this relationship at its most fundamental level holds potential for developing concepts of habitability and biosignatures that can optimize astrobiological exploration strategies and are extensible to all life.

  7. Effects of Asphalt Mix Design Properties on Pavement Performance: A Mechanistic Approach

    Directory of Open Access Journals (Sweden)

    Ahmad M. Abu Abdo

    2016-01-01

    Full Text Available The main objective of this study was to investigate the effects of hot mix asphalt material properties on the performance of flexible pavements via mechanistic approach. 3D Move Analysis software was utilized to determine rutting and cracking distresses in an asphalt concrete (AC layer. Fourteen different Superpave mixes were evaluated by utilizing results of the Dynamic Modulus (|E⁎| Test and the Dynamic Shear Modulus (|G⁎| Test. Results showed that with the increase of binder content, the tendency of rutting in AC layer increased. However, with the increase of binder content, the cracking of AC layer lessened. Furthermore, when different binder grades were evaluated, results showed that with the increase of the upper binder grade number, rutting decreased, and with the increase of the lower binder grade number, rutting increased. Furthermore, analysis showed that with the increase of the lower binder grade number, higher percent of bottom up cracks would result. As a result of the analysis, binder grade should not be solely considered for cracking in AC layer; binder content and aggregate structure play a big role. Finally, results illustrated that the mechanistic approach is a better tool to determine the performance of asphalt pavement than commonly used methods.

  8. Assessing causal mechanistic interactions: a peril ratio index of synergy based on multiplicativity.

    Directory of Open Access Journals (Sweden)

    Wen-Chung Lee

    Full Text Available The assessments of interactions in epidemiology have traditionally been based on risk-ratio, odds-ratio or rate-ratio multiplicativity. However, many epidemiologists fail to recognize that this is mainly for statistical conveniences and often will misinterpret a statistically significant interaction as a genuine mechanistic interaction. The author adopts an alternative metric system for risk, the 'peril'. A peril is an exponentiated cumulative rate, or simply, the inverse of a survival (risk complement or one plus an odds. The author proposes a new index based on multiplicativity of peril ratios, the 'peril ratio index of synergy based on multiplicativity' (PRISM. Under the assumption of no redundancy, PRISM can be used to assess synergisms in sufficient cause sense, i.e., causal co-actions or causal mechanistic interactions. It has a less stringent threshold to detect a synergy as compared to a previous index of 'relative excess risk due to interaction'. Using the new PRISM criterion, many situations in which there is not evidence of interaction judged by the traditional indices are in fact corresponding to bona fide positive or negative synergisms.

  9. Assessing causal mechanistic interactions: a peril ratio index of synergy based on multiplicativity.

    Science.gov (United States)

    Lee, Wen-Chung

    2013-01-01

    The assessments of interactions in epidemiology have traditionally been based on risk-ratio, odds-ratio or rate-ratio multiplicativity. However, many epidemiologists fail to recognize that this is mainly for statistical conveniences and often will misinterpret a statistically significant interaction as a genuine mechanistic interaction. The author adopts an alternative metric system for risk, the 'peril'. A peril is an exponentiated cumulative rate, or simply, the inverse of a survival (risk complement) or one plus an odds. The author proposes a new index based on multiplicativity of peril ratios, the 'peril ratio index of synergy based on multiplicativity' (PRISM). Under the assumption of no redundancy, PRISM can be used to assess synergisms in sufficient cause sense, i.e., causal co-actions or causal mechanistic interactions. It has a less stringent threshold to detect a synergy as compared to a previous index of 'relative excess risk due to interaction'. Using the new PRISM criterion, many situations in which there is not evidence of interaction judged by the traditional indices are in fact corresponding to bona fide positive or negative synergisms.

  10. Mutual Dependence Between Sedimentary Organic Carbon and Infaunal Macrobenthos Resolved by Mechanistic Modeling

    Science.gov (United States)

    Zhang, Wenyan; Wirtz, Kai

    2017-10-01

    The mutual dependence between sedimentary total organic carbon (TOC) and infaunal macrobenthos is here quantified by a mechanistic model. The model describes (i) the vertical distribution of infaunal macrobenthic biomass resulting from a trade-off between nutritional benefit (quantity and quality of TOC) and the costs of burial (respiration) and mortality, and (ii) the variable vertical distribution of TOC being in turn shaped by bioturbation of local macrobenthos. In contrast to conventional approaches, our model emphasizes variations of bioturbation both spatially and temporally depending on local food resources and macrobenthic biomass. Our implementation of the dynamic interaction between TOC and infaunal macrobenthos is able to capture a temporal benthic response to both depositional and erosional environments and provides improved estimates of the material exchange flux at the sediment-water interface. Applications to literature data for the North Sea demonstrate the robustness and accuracy of the model and its potential as an analysis tool for the status of TOC and macrobenthos in marine sediments. Results indicate that the vertical distribution of infaunal biomass is shaped by both the quantity and the quality of OC, while the community structure is determined only by the quality of OC. Bioturbation intensity may differ by 1 order of magnitude over different seasons owing to variations in the OC input, resulting in a significant modulation on the distribution of OC. Our relatively simple implementation may further improve models of early diagenesis and marine food web dynamics by mechanistically connecting the vertical distribution of both TOC and macrobenthic biomass.

  11. Safety, Efficacy, and Mechanistic Studies Regarding Citrus aurantium (Bitter Orange) Extract and p-Synephrine.

    Science.gov (United States)

    Stohs, Sidney J

    2017-10-01

    Citrus aurantium L. (bitter orange) extracts that contain p-synephrine as the primary protoalkaloid are widely used for weight loss/weight management, sports performance, appetite control, energy, and mental focus and cognition. Questions have been raised about the safety of p-synephrine because it has some structural similarity to ephedrine. This review focuses on current human, animal, in vitro, and mechanistic studies that address the safety, efficacy, and mechanisms of action of bitter orange extracts and p-synephrine. Numerous studies have been conducted with respect to p-synephrine and bitter orange extract because ephedra and ephedrine were banned from use in dietary supplements in 2004. Approximately 30 human studies indicate that p-synephrine and bitter orange extracts do not result in cardiovascular effects and do not act as stimulants at commonly used doses. Mechanistic studies suggest that p-synephrine exerts its effects through multiple actions, which are discussed. Because p-synephrine exhibits greater adrenergic receptor binding in rodents than humans, data from animals cannot be directly extrapolated to humans. This review, as well as several other assessments published in recent years, has concluded that bitter orange extract and p-synephrine are safe for use in dietary supplements and foods at the commonly used doses. Copyright © 2017 The Authors Phytotherapy Research Published by John Wiley & Sons Ltd. Copyright © 2017 The Authors Phytotherapy Research Published by John Wiley & Sons Ltd.

  12. Safety, Efficacy, and Mechanistic Studies Regarding Citrus aurantium (Bitter Orange) Extract and p‐Synephrine

    Science.gov (United States)

    2017-01-01

    Citrus aurantium L. (bitter orange) extracts that contain p‐synephrine as the primary protoalkaloid are widely used for weight loss/weight management, sports performance, appetite control, energy, and mental focus and cognition. Questions have been raised about the safety of p‐synephrine because it has some structural similarity to ephedrine. This review focuses on current human, animal, in vitro, and mechanistic studies that address the safety, efficacy, and mechanisms of action of bitter orange extracts and p‐synephrine. Numerous studies have been conducted with respect to p‐synephrine and bitter orange extract because ephedra and ephedrine were banned from use in dietary supplements in 2004. Approximately 30 human studies indicate that p‐synephrine and bitter orange extracts do not result in cardiovascular effects and do not act as stimulants at commonly used doses. Mechanistic studies suggest that p‐synephrine exerts its effects through multiple actions, which are discussed. Because p‐synephrine exhibits greater adrenergic receptor binding in rodents than humans, data from animals cannot be directly extrapolated to humans. This review, as well as several other assessments published in recent years, has concluded that bitter orange extract and p‐synephrine are safe for use in dietary supplements and foods at the commonly used doses. Copyright © 2017 The Authors Phytotherapy Research Published by John Wiley & Sons Ltd. PMID:28752649

  13. SITE-94. Adaptation of mechanistic sorption models for performance assessment calculations

    International Nuclear Information System (INIS)

    Arthur, R.C.

    1996-10-01

    Sorption is considered in most predictive models of radionuclide transport in geologic systems. Most models simulate the effects of sorption in terms of empirical parameters, which however can be criticized because the data are only strictly valid under the experimental conditions at which they were measured. An alternative is to adopt a more mechanistic modeling framework based on recent advances in understanding the electrical properties of oxide mineral-water interfaces. It has recently been proposed that these 'surface-complexation' models may be directly applicable to natural systems. A possible approach for adapting mechanistic sorption models for use in performance assessments, using this 'surface-film' concept, is described in this report. Surface-acidity parameters in the Generalized Two-Layer surface complexation model are combined with surface-complexation constants for Np(V) sorption ob hydrous ferric oxide to derive an analytical model enabling direct calculation of corresponding intrinsic distribution coefficients as a function of pH, and Ca 2+ , Cl - , and HCO 3 - concentrations. The surface film concept is then used to calculate whole-rock distribution coefficients for Np(V) sorption by altered granitic rocks coexisting with a hypothetical, oxidized Aespoe groundwater. The calculated results suggest that the distribution coefficients for Np adsorption on these rocks could range from 10 to 100 ml/g. Independent estimates of K d for Np sorption in similar systems, based on an extensive review of experimental data, are consistent, though slightly conservative, with respect to the calculated values. 31 refs

  14. A Mechanistic Reliability Assessment of RVACS and Metal Fuel Inherent Reactivity Feedbacks

    Energy Technology Data Exchange (ETDEWEB)

    Grabaskas, David; Brunett, Acacia J.; Passerini, Stefano; Grelle, Austin

    2017-09-24

    GE Hitachi Nuclear Energy (GEH) and Argonne National Laboratory (Argonne) participated in a two year collaboration to modernize and update the probabilistic risk assessment (PRA) for the PRISM sodium fast reactor. At a high level, the primary outcome of the project was the development of a next-generation PRA that is intended to enable risk-informed prioritization of safety- and reliability-focused research and development. A central Argonne task during this project was a reliability assessment of passive safety systems, which included the Reactor Vessel Auxiliary Cooling System (RVACS) and the inherent reactivity feedbacks of the metal fuel core. Both systems were examined utilizing a methodology derived from the Reliability Method for Passive Safety Functions (RMPS), with an emphasis on developing success criteria based on mechanistic system modeling while also maintaining consistency with the Fuel Damage Categories (FDCs) of the mechanistic source term assessment. This paper provides an overview of the reliability analyses of both systems, including highlights of the FMEAs, the construction of best-estimate models, uncertain parameter screening and propagation, and the quantification of system failure probability. In particular, special focus is given to the methodologies to perform the analysis of uncertainty propagation and the determination of the likelihood of violating FDC limits. Additionally, important lessons learned are also reviewed, such as optimal sampling methodologies for the discovery of low likelihood failure events and strategies for the combined treatment of aleatory and epistemic uncertainties.

  15. Mechanistic study of manganese-substituted glycerol dehydrogenase using a kinetic and thermodynamic analysis.

    Directory of Open Access Journals (Sweden)

    Baishan Fang

    Full Text Available Mechanistic insights regarding the activity enhancement of dehydrogenase by metal ion substitution were investigated by a simple method using a kinetic and thermodynamic analysis. By profiling the binding energy of both the substrate and product, the metal ion's role in catalysis enhancement was revealed. Glycerol dehydrogenase (GDH from Klebsiella pneumoniae sp., which demonstrated an improvement in activity by the substitution of a zinc ion with a manganese ion, was used as a model for the mechanistic study of metal ion substitution. A kinetic model based on an ordered Bi-Bi mechanism was proposed considering the noncompetitive product inhibition of dihydroxyacetone (DHA and the competitive product inhibition of NADH. By obtaining preliminary kinetic parameters of substrate and product inhibition, the number of estimated parameters was reduced from 10 to 4 for a nonlinear regression-based kinetic parameter estimation. The simulated values of time-concentration curves fit the experimental values well, with an average relative error of 11.5% and 12.7% for Mn-GDH and GDH, respectively. A comparison of the binding energy of enzyme ternary complex for Mn-GDH and GDH derived from kinetic parameters indicated that metal ion substitution accelerated the release of dioxyacetone. The metal ion's role in catalysis enhancement was explicated.

  16. Comparison of Two-Phase Pipe Flow in OpenFOAM with a Mechanistic Model

    Science.gov (United States)

    Shuard, Adrian M.; Mahmud, Hisham B.; King, Andrew J.

    2016-03-01

    Two-phase pipe flow is a common occurrence in many industrial applications such as power generation and oil and gas transportation. Accurate prediction of liquid holdup and pressure drop is of vast importance to ensure effective design and operation of fluid transport systems. In this paper, a Computational Fluid Dynamics (CFD) study of a two-phase flow of air and water is performed using OpenFOAM. The two-phase solver, interFoam is used to identify flow patterns and generate values of liquid holdup and pressure drop, which are compared to results obtained from a two-phase mechanistic model developed by Petalas and Aziz (2002). A total of 60 simulations have been performed at three separate pipe inclinations of 0°, +10° and -10° respectively. A three dimensional, 0.052m diameter pipe of 4m length is used with the Shear Stress Transport (SST) k - ɷ turbulence model to solve the turbulent mixtures of air and water. Results show that the flow pattern behaviour and numerical values of liquid holdup and pressure drop compare reasonably well to the mechanistic model.

  17. Comparison of Two-Phase Pipe Flow in OpenFOAM with a Mechanistic Model

    International Nuclear Information System (INIS)

    Shuard, Adrian M; Mahmud, Hisham B; King, Andrew J

    2016-01-01

    Two-phase pipe flow is a common occurrence in many industrial applications such as power generation and oil and gas transportation. Accurate prediction of liquid holdup and pressure drop is of vast importance to ensure effective design and operation of fluid transport systems. In this paper, a Computational Fluid Dynamics (CFD) study of a two-phase flow of air and water is performed using OpenFOAM. The two-phase solver, interFoam is used to identify flow patterns and generate values of liquid holdup and pressure drop, which are compared to results obtained from a two-phase mechanistic model developed by Petalas and Aziz (2002). A total of 60 simulations have been performed at three separate pipe inclinations of 0°, +10° and -10° respectively. A three dimensional, 0.052m diameter pipe of 4m length is used with the Shear Stress Transport (SST) k - ω turbulence model to solve the turbulent mixtures of air and water. Results show that the flow pattern behaviour and numerical values of liquid holdup and pressure drop compare reasonably well to the mechanistic model. (paper)

  18. Mechanistic Studies at the Interface Between Organometallic Chemistry and Homogeneous Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Casey, Charles P

    2012-11-14

    Mechanistic Studies at the Interface Between Organometallic Chemistry and Homogeneous Catalysis Charles P. Casey, Principal Investigator Department of Chemistry, University of Wisconsin - Madison, Madison, Wisconsin 53706 Phone 608-262-0584 FAX: 608-262-7144 Email: casey@chem.wisc.edu http://www.chem.wisc.edu/main/people/faculty/casey.html Executive Summary. Our goal was to learn the intimate mechanistic details of reactions involved in homogeneous catalysis and to use the insight we gain to develop new and improved catalysts. Our work centered on the hydrogenation of polar functional groups such as aldehydes and ketones and on hydroformylation. Specifically, we concentrated on catalysts capable of simultaneously transferring hydride from a metal center and a proton from an acidic oxygen or nitrogen center to an aldehyde or ketone. An economical iron based catalyst was developed and patented. Better understanding of fundamental organometallic reactions and catalytic processes enabled design of energy and material efficient chemical processes. Our work contributed to the development of catalysts for the selective and mild hydrogenation of ketones and aldehydes; this will provide a modern green alternative to reductions by LiAlH4 and NaBH4, which require extensive work-up procedures and produce waste streams. (C5R4OH)Ru(CO)2H Hydrogenation Catalysts. Youval Shvo described a remarkable catalytic system in which the key intermediate (C5R4OH)Ru(CO)2H (1) has an electronically coupled acidic OH unit and a hydridic RuH unit. Our efforts centered on understanding and improving upon this important catalyst for reduction of aldehydes and ketones. Our mechanistic studies established that the reduction of aldehydes by 1 to produce alcohols and a diruthenium bridging hydride species occurs much more rapidly than regeneration of the ruthenium hydride from the diruthenium bridging hydride species. Our mechanistic studies require simultaneous transfer of hydride from ruthenium to

  19. Joint Integrated Air Defense Systems View (J-IADS-VIEW)

    National Research Council Canada - National Science Library

    Sutton, Mike

    2006-01-01

    ...) was developed over a two year span. J-IADS-View is an automated computer program that equips the information operations analyst with a tool to create dynamic and animated visual of foreign threat IADS information...

  20. The STAPL pView

    KAUST Repository

    Buss, Antal

    2011-01-01

    The Standard Template Adaptive Parallel Library (STAPL) is a C++ parallel programming library that provides a collection of distributed data structures (pContainers) and parallel algorithms (pAlgorithms) and a generic methodology for extending them to provide customized functionality. STAPL algorithms are written in terms of pViews, which provide a generic access interface to pContainer data by abstracting common data structure concepts. Briefly, pViews allow the same pContainer to present multiple interfaces, e.g., enabling the same pMatrix to be \\'viewed\\' (or used) as a row-major or column-major matrix, or even as a vector. In this paper, we describe the stapl pView concept and its properties. pViews generalize the iterator concept and enable parallelism by providing random access to, and an ADT for, collections of elements. We illustrate how pViews provide support for managing the tradeoff between expressivity and performance and examine the performance overhead incurred when using pViews. © 2011 Springer-Verlag Berlin Heidelberg.

  1. Advanced LabVIEW Labs

    International Nuclear Information System (INIS)

    Jones, Eric D.

    1999-01-01

    In the world of computer-based data acquisition and control, the graphical interface program LabVIEW from National Instruments is so ubiquitous that in many ways it has almost become the laboratory standard. To date, there have been approximately fifteen books concerning LabVIEW, but Professor Essick's treatise takes on a completely different tack than all of the previous discussions. In the more standard treatments of the ways and wherefores of LabVIEW such as LabVIEW Graphical Programming: Practical Applications in Instrumentation and Control by Gary W. Johnson (McGraw Hill, NY 1997), the emphasis has been instructing the reader how to program LabVIEW to create a Virtual Instrument (VI) on the computer for interfacing to a particular instruments. LabVIEW is written in ''G'' a graphical programming language developed by National Instruments. In the past the emphasis has been on training the experimenter to learn ''G''. Without going into details here, ''G'' incorporates the usual loops, arithmetic expressions, etc., found in many programming languages, but in an icon (graphical) environment. The net result being that LabVIEW contains all of the standard methods needed for interfacing to instruments, data acquisition, data analysis, graphics, and also methodology to incorporate programs written in other languages into LabVIEW. Historically, according to Professor Essick, he developed a series of experiments for an upper division laboratory course for computer-based instrumentation. His observation was that while many students had the necessary background in computer programming languages, there were students who had virtually no concept about writing a computer program let alone a computer- based interfacing program. Thus the beginnings of a concept for not only teaching computer- based instrumentation techniques, but aiso a method for the beginner to experience writing a com- puter program. Professor Essick saw LabVIEW as the ''perfect environment in which to

  2. Mechanistic models of plant seed dispersal by wind in heterogeneous landscapes

    Science.gov (United States)

    Trakhtenbrot, A.; Katul, G. G.; Nathan, R.

    2010-12-01

    Seed dispersal, and especially long-distance dispersal (LDD), is a key process in plant population survival, colonization, and gene flow. Its importance is amplified by the man-induced habitat fragmentation, climate change and invasions of exotic species. Mechanistic seed dispersal models are central to quantitative prediction of dispersal patterns and understanding their underlying mechanisms. For wind dispersal, most current mechanistic models assume homogenous environment. Although both topography and sharp transitions in vegetation stature profoundly affect wind flow, accounting for these effects via simplified models remains a vexing research problem. Such simplified models are needed to inform ecosystem managers about consequences of landscape fragmentation. We modified the Coupled Eulerian-Lagrangian closure (CELC) mechanistic dispersal model to represent scenarios of wind flow over a sharp transition from short to tall vegetation or over forested hilly terrain, and predicted the resulting dispersal distances and direction. We parameterized the wind and vegetation factors using measurements taken on a hill with short height Mediterranean shrubland and pine forest vegetation at Mt. Pithulim, Israel. For the short-to-tall vegetation transition scenario, the main feature of the modeled wind field is an exponential decay of the mean horizontal wind velocity, assuming that the mean momentum equation simplifies to a balance between the advective acceleration and the drag force terms. As a consequence of the incompressibility condition, this exponential decay leads to strong upward mean vertical velocity component. We found that for seed release downwind of the edge, the simulated median (short) and 99-th percentile (long) distances were longer than those for the homogeneous tall vegetation scenario. For seed release upwind of the edge the effect on dispersal distance was more complex and depended on the release height and he seed terminal velocity of the seeds

  3. Linking spring phenology with mechanistic models of host movement to predict disease transmission risk

    Science.gov (United States)

    Merkle, Jerod A.; Cross, Paul C.; Scurlock, Brandon M.; Cole, Eric K.; Courtemanch, Alyson B.; Dewey, Sarah R.; Kauffman, Matthew J.

    2018-01-01

    Disease models typically focus on temporal dynamics of infection, while often neglecting environmental processes that determine host movement. In many systems, however, temporal disease dynamics may be slow compared to the scale at which environmental conditions alter host space-use and accelerate disease transmission.Using a mechanistic movement modelling approach, we made space-use predictions of a mobile host (elk [Cervus Canadensis] carrying the bacterial disease brucellosis) under environmental conditions that change daily and annually (e.g., plant phenology, snow depth), and we used these predictions to infer how spring phenology influences the risk of brucellosis transmission from elk (through aborted foetuses) to livestock in the Greater Yellowstone Ecosystem.Using data from 288 female elk monitored with GPS collars, we fit step selection functions (SSFs) during the spring abortion season and then implemented a master equation approach to translate SSFs into predictions of daily elk distribution for five plausible winter weather scenarios (from a heavy snow, to an extreme winter drought year). We predicted abortion events by combining elk distributions with empirical estimates of daily abortion rates, spatially varying elk seroprevelance and elk population counts.Our results reveal strong spatial variation in disease transmission risk at daily and annual scales that is strongly governed by variation in host movement in response to spring phenology. For example, in comparison with an average snow year, years with early snowmelt are predicted to have 64% of the abortions occurring on feedgrounds shift to occurring on mainly public lands, and to a lesser extent on private lands.Synthesis and applications. Linking mechanistic models of host movement with disease dynamics leads to a novel bridge between movement and disease ecology. Our analysis framework offers new avenues for predicting disease spread, while providing managers tools to proactively mitigate

  4. Experts views' on Digital Competence

    NARCIS (Netherlands)

    Janssen, José; Stoyanov, Slavi

    2013-01-01

    Janssen, J., & Stoyanov, S. (2012, 20 November). Online Consultation for a Digital Competence Framework: Experts' views on Digital Competence. Workshop presentation at the Institute for Prospective Technological Studies, Seville, Spain.

  5. "Private Views" Ungaris / Katrin Kivimaa

    Index Scriptorium Estoniae

    Kivimaa, Katrin, 1969-

    1999-01-01

    Inglise ja eesti kunstnike ühisprojekt 8. augustini Dunaujvarosi Kaasaegse Kunsti Instituudis Ungaris. Kuraatorid Pam Skelton, Mare Tralla. "Private Views" ülesandeks on keskenduda ruumi mõistele naiskunstniku pilgu läbi

  6. 'Private Views' Ungaris / Katrin Kivimaa

    Index Scriptorium Estoniae

    Kivimaa, Katrin, 1969-

    1999-01-01

    Inglise js eesti kunstnike ühisprojekt 8. augustini Dunaujvarosi Kaasaegse Kunsti Instituudis Ungaris. Kuraatorid Pam Skelton, Mare Tralla. 'Private Views' ülesandeks on keskenduda ruumi mõistele naiskunstniku pilgu läbi.

  7. A broader view of justice.

    Science.gov (United States)

    Jecker, Nancy S

    2008-10-01

    In this paper I argue that a narrow view of justice dominates the bioethics literature. I urge a broader view. As bioethicists, we often conceive of justice using a medical model. This model focuses attention at a particular point in time, namely, when someone who is already sick seeks access to scarce or expensive services. A medical model asks how we can fairly distribute those services. The broader view I endorse requires looking upstream, and asking how disease and suffering came about. In contrast to a medical model, a social model of justice considers how social determinants affect the health of a population. For example, social factors such as access to clean drinking water, education, safe workplaces, and police protection, profoundly affect risk for disease and early death. I examine one important social determinant of health, health care coverage, to show the limits of a medical model and the merits of a broader view.

  8. Combining Solvent Isotope Effects with Substrate Isotope Effects in Mechanistic Studies of Alcohol and Amine Oxidation by Enzymes*

    Science.gov (United States)

    Fitzpatrick, Paul F.

    2014-01-01

    Oxidation of alcohols and amines is catalyzed by multiple families of flavin-and pyridine nucleotide-dependent enzymes. Measurement of solvent isotope effects provides a unique mechanistic probe of the timing of the cleavage of the OH and NH bonds, necessary information for a complete description of the catalytic mechanism. The inherent ambiguities in interpretation of solvent isotope effects can be significantly decreased if isotope effects arising from isotopically labeled substrates are measured in combination with solvent isotope effects. The application of combined solvent and substrate (mainly deuterium) isotope effects to multiple enzymes is described here to illustrate the range of mechanistic insights that such an approach can provide. PMID:25448013

  9. Mechanistic evidence for a ring-opening pathway in the Pd-catalyzed direct arylation of benzoxazoles

    DEFF Research Database (Denmark)

    Sanchez, R.S.; Zhuravlev, Fedor

    2007-01-01

    The direct Pd-catalyzed arylation of 5-substituted benzoxazoles, used as a mechanistic model for 1,3-azoles, was investigated experimentally and computationally. The results of the primary deuterium kinetic isotope effect, Hammett studies, and H/D exchange were shown to be inconsistent with the r......The direct Pd-catalyzed arylation of 5-substituted benzoxazoles, used as a mechanistic model for 1,3-azoles, was investigated experimentally and computationally. The results of the primary deuterium kinetic isotope effect, Hammett studies, and H/D exchange were shown to be inconsistent...

  10. Formulation and process strategies to minimize coat damage for compaction of coated pellets in a rotary tablet press: A mechanistic view.

    Science.gov (United States)

    Xu, Min; Heng, Paul Wan Sia; Liew, Celine Valeria

    2016-02-29

    Compaction of multiple-unit pellet system (MUPS) tablets has been extensively studied in the past few decades but with marginal success. This study aims to investigate the formulation and process strategies for minimizing pellet coat damage caused by compaction and elucidate the mechanism of damage sustained during the preparation of MUPS tablets in a rotary tablet press. Blends containing ethylcellulose-coated pellets and cushioning agent (spray dried aggregates of micronized lactose and mannitol), were compacted into MUPS tablets in a rotary tablet press. The effects of compaction pressure and dwell time on the physicomechanical properties of resultant MUPS tablets and extent of pellet coat damage were systematically examined. The coated pellets from various locations at the axial and radial peripheral surfaces and core of the MUPS tablets were excavated and assessed for their coat damage individually. Interestingly, for a MUPS tablet formulation which consolidates by plastic deformation, the tablet mechanical strength could be enhanced without exacerbating pellet coat damage by extending the dwell time in the compaction cycle during rotary tableting. However, the increase in compaction pressure led to faster drug release rate. The location of the coated pellets in the MUPS tablet also contributed to the extent of their coat damage, possibly due to uneven force distribution within the compact. To ensure viability of pellet coat integrity, the formation of a continuous percolating network of cushioning agent is critical and the applied compaction pressure should be less than the pellet crushing strength. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Ways of Viewing Pictorial Plasticity

    OpenAIRE

    Wijntjes, Maarten W. A.

    2017-01-01

    The plastic effect is historically used to denote various forms of stereopsis. The vivid impression of depth often associated with binocular stereopsis can also be achieved in other ways, for example, using a synopter. Accounts of this go back over a hundred years. These ways of viewing all aim to diminish sensorial evidence that the picture is physically flat. Although various viewing modes have been proposed in the literature, their effects have never been compared. In the current study, we...

  12. Mechanistic studies of copper(I)-catalyzed 1,3-halogen migration.

    Science.gov (United States)

    Van Hoveln, Ryan; Hudson, Brandi M; Wedler, Henry B; Bates, Desiree M; Le Gros, Gabriel; Tantillo, Dean J; Schomaker, Jennifer M

    2015-04-29

    An ongoing challenge in modern catalysis is to identify and understand new modes of reactivity promoted by earth-abundant and inexpensive first-row transition metals. Herein, we report a mechanistic study of an unusual copper(I)-catalyzed 1,3-migration of 2-bromostyrenes that reincorporates the bromine activating group into the final product with concomitant borylation of the aryl halide bond. A combination of experimental and computational studies indicated this reaction does not involve any oxidation state changes at copper; rather, migration occurs through a series of formal sigmatropic shifts. Insight provided from these studies will be used to expand the utility of aryl copper species in synthesis and develop new ligands for enantioselective copper-catalyzed halogenation.

  13. Combating Pathogenic Microorganisms Using Plant-Derived Antimicrobials: A Minireview of the Mechanistic Basis

    Directory of Open Access Journals (Sweden)

    Abhinav Upadhyay

    2014-01-01

    Full Text Available The emergence of antibiotic resistance in pathogenic bacteria has led to renewed interest in exploring the potential of plant-derived antimicrobials (PDAs as an alternative therapeutic strategy to combat microbial infections. Historically, plant extracts have been used as a safe, effective, and natural remedy for ailments and diseases in traditional medicine. Extensive research in the last two decades has identified a plethora of PDAs with a wide spectrum of activity against a variety of fungal and bacterial pathogens causing infections in humans and animals. Active components of many plant extracts have been characterized and are commercially available; however, research delineating the mechanistic basis of their antimicrobial action is scanty. This review highlights the potential of various plant-derived compounds to control pathogenic bacteria, especially the diverse effects exerted by plant compounds on various virulence factors that are critical for pathogenicity inside the host. In addition, the potential effect of PDAs on gut microbiota is discussed.

  14. A Mechanistic Source Term Calculation for a Metal Fuel Sodium Fast Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Grabaskas, David; Bucknor, Matthew; Jerden, James

    2017-06-26

    A mechanistic source term (MST) calculation attempts to realistically assess the transport and release of radionuclides from a reactor system to the environment during a specific accident sequence. The U.S. Nuclear Regulatory Commission (NRC) has repeatedly stated its expectation that advanced reactor vendors will utilize an MST during the U.S. reactor licensing process. As part of a project to examine possible impediments to sodium fast reactor (SFR) licensing in the U.S., an analysis was conducted regarding the current capabilities to perform an MST for a metal fuel SFR. The purpose of the project was to identify and prioritize any gaps in current computational tools, and the associated database, for the accurate assessment of an MST. The results of the study demonstrate that an SFR MST is possible with current tools and data, but several gaps exist that may lead to possibly unacceptable levels of uncertainty, depending on the goals of the MST analysis.

  15. Mechanistic insights into the 1,3-xylanases: useful enzymes for manipulation of algal biomass.

    Science.gov (United States)

    Goddard-Borger, Ethan D; Sakaguchi, Keishi; Reitinger, Stephan; Watanabe, Nobuhisa; Ito, Makoto; Withers, Stephen G

    2012-02-29

    Xylanases capable of degrading the crystalline microfibrils of 1,3-xylan that reinforce the cell walls of some red and siphonous green algae have not been well studied, yet they could prove to be of great utility in algaculture for the production of food and renewable chemical feedstocks. To gain a better mechanistic understanding of these enzymes, a suite of reagents was synthesized and evaluated as substrates and inhibitors of an endo-1,3-xylanase. With these reagents, a retaining mechanism was confirmed for the xylanase, its catalytic nucleophile identified, and the existence of -3 to +2 substrate-binding subsites demonstrated. Protein crystal X-ray diffraction methods provided a high resolution structure of a trapped covalent glycosyl-enzyme intermediate, indicating that the 1,3-xylanases likely utilize the (1)S(3) → (4)H(3) → (4)C(1) conformational itinerary to effect catalysis. © 2012 American Chemical Society

  16. A comprehensive mechanistic model for simulating algal-bacterial growth dynamics in photobioreactors.

    Science.gov (United States)

    Shriwastav, Amritanshu; Ashok, Vaishali; Thomas, Jeenu; Bose, Purnendu

    2018-01-01

    A comprehensive mechanistic model with state of the art understanding and assumptions is presented to simulate major processes in a photobioreactor for describing the algal-bacterial growth dynamics. The model includes a total of 37 state variables that broadly cover all the essential physiological and physico-chemical processes in such a system. Model parameters are first calibrated with batch experimental data, and thereafter, extensive validation of the model is carried with long term independent experimental data in diverse conditions. The developed model is able to capture the complex system behavior with reasonable accuracy. Also, the comprehensive mathematical formulation with realistic assumptions make this model a valuable tool for gaining better insights into the complex system behavior. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Pollution and skin: from epidemiological and mechanistic studies to clinical implications.

    Science.gov (United States)

    Krutmann, Jean; Liu, Wei; Li, Li; Pan, Xiaochuan; Crawford, Martha; Sore, Gabrielle; Seite, Sophie

    2014-12-01

    In recent years, the health effects associated with air pollution have been intensively studied. Most studies focus on air pollution effects on the lung and the cardiovascular system. More recently, however, epidemiological and mechanistic studies suggest that air pollution is also affecting skin integrity. This state-of-the-art review focuses on this latter aspect; it was developed with the collaboration of European and Chinese board of experts with specific interests in environmental health, clinical and basic research in dermatology and cosmetic dermatology. A literature review limited to pollution and health effects and (sensitive) skin was performed using PubMed. Review and original articles were chosen. We summarize the existing scientific evidence that air pollution exerts detrimental effects on human skin, discuss potential clinical implications and suggest specific and unspecific cosmetic protective measures. Copyright © 2014 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.

  18. Structural and mechanistic basis of differentiated inhibitors of the acute pancreatitis target kynurenine-3-monooxygenase

    Science.gov (United States)

    Hutchinson, Jonathan P.; Rowland, Paul; Taylor, Mark R. D.; Christodoulou, Erica M.; Haslam, Carl; Hobbs, Clare I.; Holmes, Duncan S.; Homes, Paul; Liddle, John; Mole, Damian J.; Uings, Iain; Walker, Ann L.; Webster, Scott P.; Mowat, Christopher G.; Chung, Chun-Wa

    2017-06-01

    Kynurenine-3-monooxygenase (KMO) is a key FAD-dependent enzyme of tryptophan metabolism. In animal models, KMO inhibition has shown benefit in neurodegenerative diseases such as Huntington's and Alzheimer's. Most recently it has been identified as a target for acute pancreatitis multiple organ dysfunction syndrome (AP-MODS); a devastating inflammatory condition with a mortality rate in excess of 20%. Here we report and dissect the molecular mechanism of action of three classes of KMO inhibitors with differentiated binding modes and kinetics. Two novel inhibitor classes trap the catalytic flavin in a previously unobserved tilting conformation. This correlates with picomolar affinities, increased residence times and an absence of the peroxide production seen with previous substrate site inhibitors. These structural and mechanistic insights culminated in GSK065(C1) and GSK366(C2), molecules suitable for preclinical evaluation. Moreover, revising the repertoire of flavin dynamics in this enzyme class offers exciting new opportunities for inhibitor design.

  19. Exposure factors for marine eutrophication impacts assessment based on a mechanistic biological model

    DEFF Research Database (Denmark)

    Cosme, Nuno Miguel Dias; Koski, Marja; Hauschild, Michael Zwicky

    2015-01-01

    routes from primary (cell aggregates) and secondary producers (faecal pellets, carcasses, and active vertical transport). Carbon export production (PE) and ecosystems eXposure Factors (XF), which represents a nitrogen-to-oxygen 'conversion' potential, were estimated at a spatial resolution of 66 large......Emissions of nitrogen (N) from anthropogenic sources enrich marine waters and promote planktonic growth. This newly synthesised organic carbon is eventually exported to benthic waters where aerobic respiration by heterotrophic bacteria results in the consumption of dissolved oxygen (DO......). This pathway is typical of marine eutrophication. A model is proposed to mechanistically estimate the response of coastal marine ecosystems to N inputs. It addresses the biological processes of nutrient-limited primary production (PP), metazoan consumption, and bacterial degradation, in four distinct sinking...

  20. Improving Predictive Modeling in Pediatric Drug Development: Pharmacokinetics, Pharmacodynamics, and Mechanistic Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Slikker, William; Young, John F.; Corley, Rick A.; Dorman, David C.; Conolly, Rory B.; Knudsen, Thomas; Erstad, Brian L.; Luecke, Richard H.; Faustman, Elaine M.; Timchalk, Chuck; Mattison, Donald R.

    2005-07-26

    A workshop was conducted on November 18?19, 2004, to address the issue of improving predictive models for drug delivery to developing humans. Although considerable progress has been made for adult humans, large gaps remain for predicting pharmacokinetic/pharmacodynamic (PK/PD) outcome in children because most adult models have not been tested during development. The goals of the meeting included a description of when, during development, infants/children become adultlike in handling drugs. The issue of incorporating the most recent advances into the predictive models was also addressed: both the use of imaging approaches and genomic information were considered. Disease state, as exemplified by obesity, was addressed as a modifier of drug pharmacokinetics and pharmacodynamics during development. Issues addressed in this workshop should be considered in the development of new predictive and mechanistic models of drug kinetics and dynamics in the developing human.