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Engineering and Technology, Mechanical Engineering, Applied Mechanics, Teknik och teknologier, Maskinteknik, Teknisk mekanik, Hållfasthetslära, Solid Mechanics, Simulering av klippning i höghållfast stål, Sheet metal, Experiment, Shearing, Force, Clearance, and Angle

Shearing is a fast and inexpensive method to cut sheet metal that has been used since the beginning of the industrialism. Consequently, published experimental studies of shearing can be found from over a century back in time. Recent studies, however, are due to the availability of low cost digital computation power, mostly based on finite element simulations that guarantees quick results. Still, for validation of models and simulations, accurate experimental data is a requisite. When applicable, 2D models are in general desirable over 3D models because of advantages like low computation time and easy model formulation. Shearing of sheet metal with parallel tools is successfully modelled in 2D with a plane strain approximation, but with angled tools the approximation is less obvious. Therefore, plane strain approximations for shearing with angled tools were evaluated by shear experiments of high accuracy. Tool angle, tool clearance, and clamping of the sheet were varied in the experiments. The results showed that the measured forces in shearing with angled tools can be approximately calculated using force measurements from shearing with parallel tools. Shearing energy was introduced as a quantifiable measure of suitable tool clearance range. The effects of the shearing parameters on forces were in agreement with previous studies. Based on the agreement between calculations and experiments, analysis based on a plane strain assumption is considered applicable for angled tools with a small (up to 2 degrees) rake angle.

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Biochemistry, molecular biology, biophysics, Biochimie, biologie moléculaire, biophysique, Ecology, Ecologie, Geology, Géologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Ecologie animale, vegetale et microbienne, Animal, plant and microbial ecology, Ecologie microbienne, Microbial ecology, Milieux divers (espace extraatmosphérique, air, eau), Various environments (extraatmospheric space, air, water), Bactérie, Bacteria, Article synthèse, Review, Artículo síntesis, Cyanobacteria, Cycle biogéochimique, Biogeochemical cycle, Ciclo biogeoquímico, Diazotrophie, Diazotrophy, Diazotrofía, Fixation azote, Nitrogen fixation, Fijación nitrogeno, Milieu marin, Marine environment, Medio marino, Océan, Ocean, Océano, and Trichodesmium

The surface water of the marine environment has traditionally been viewed as a nitrogen (N) limited habitat, and this has guided the development of conceptual biogeochemical models focusing largely on the reservoir of nitrate as the critical source of N to sustain primary productivity. However, selected groups of Bacteria, including cyanobacteria, and Archaea can utilize dinitrogen (N2) as an alternative N source. In the marine environment, these microorganisms can have profound effects on net community production processes and can impact the coupling of C-N-P cycles as well as the net oceanic sequestration of atmospheric carbon dioxide. As one component of an integrated 'Nitrogen Transport and Transformations' project, we have begun to re-assess our understanding of (I) the biotic sources and rates of N2 fixation in the world's oceans, (2) the major controls on rates of oceanic N2 fixation, (3) the significance of this N2 fixation for the global carbon cycle and (4) the role of human activities in the alteration of oceanic N2 fixation. Preliminary results indicate that rates of N2 fixation, especially in subtropical and tropical open ocean habitats, have a major role in the global marine N budget. Iron (Fe) bioavailability appears to be an important control and is, therefore, critical in extrapolation to global rates of N2 fixation. Anthropogenic perturbations may alter N2 fixation in coastal environments through habitat destruction and eutrophication, and open ocean N2 fixation may be enhanced by warming and increased stratification of the upper water column. Global anthropogenic and climatic changes may also affect N2 fixation rates, for example by altering dust inputs (i.e. Fe) or by expansion of subtropical boundaries. Some recent estimates of global ocean N2 fixation are in the range of 100-200 Tg N (1-2 x 1014 g N) yr-1, but have large uncertainties. These estimates are nearly an order of magnitude greater than historical, pre-1980 estimates, but approach modern estimates of oceanic denitrification.

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Biochemistry, molecular biology, biophysics, Biochimie, biologie moléculaire, biophysique, Ecology, Ecologie, Geology, Géologie, Sciences exactes et technologie, Exact sciences and technology, Terre, ocean, espace, Earth, ocean, space, Sciences de la terre, Earth sciences, Géochimie, Geochemistry, Géochimie des sols et des roches, Soil and rock geochemistry, Formations superficielles, Surficial geology, Quaternaire marin et continental, Marine and continental quaternary, Europe, Europa, Actuel, modern, Actual, Calcium, calcium, Calcio, Carbohydrate, carbohydrates, Matière particulaire, particulate matters, Partícula elemental, Milieu intertidal, intertidal environment, Medio intertidal, Particule, particles, Rhéologie, rheology, Reología, Sorption, sorption, Sorción, Stabilisation, stabilization, Estabilización, Sédimentation estuaire, estuarine sedimentation, Sedimentación estuario, Vasière, mud flats, and Marisma

Extracellular Polymeric Substances (EPS) are considered to play an important role in the stabilization of intertidal mudflats. In this study the role of EPS as a binding agent in intertidal sediments was investigated. For this purpose two EPS fractions (termed coll-SF and EDTA-SF) were isolated from intertidal sediment and characterized in terms of monosaccharide- and size distribution. In slurry addition experiments the sorption characteristics of these EPS-fractions as well as their effect on sediment properties were examined under varying Ca2+-concentrations. Results showed more EDTA-SF adsorbed to the sediment compared to coll-SF. For both fractions more EPS adsorbed to the sediment when Ca2+-concentration increased. This effect was stronger for EDTA-SF. The differences in sorption between the two fractions could not be explained in terms of monosaccharide- and size distribution, which were largely similar. The addition of EPS in the presence or absence of Ca2+ did not alter the rheology of the sediment slurries indicating that there was no effect of EPS on the sediment properties. This contradicts results of experiments with bacterial EPS as well as field observations in which the presence of EPS/ biofilms leads to an increase in the erosion resistance of the sediment. Possible causes for this discrepancy in results are discussed.

Ecology, Ecologie, Environment, Environnement, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Ecologie animale, vegetale et microbienne, Animal, plant and microbial ecology, Ecologie animale et végétale, Animal and plant ecology, Autoécologie, Autoecology, Animaux, Animals, Protozoa. Invertebrata, Arthropoda, Composé sémiochimique, Semiochemicals, Heteroptera, Insecta, Invertebrata, Pentatomidae, Allomone, Alomona, Analyse chimique, Chemical analysis, Análisis químico, Attractif, Attractant, Atractivo, Mâle, Male, Macho, Phéromone sexuelle, Sex pheromone, Feromona sexual, Structure chimique, Chemical structure, Estructura química, Tibraca limbativentris, (1RS, 4RS, 1'5)-4-(1', 5'-dimethylhex-4'-enyl)- 1-methylcyclohex-2-en-1-ol, Semiochemical, allomone, and zingiberenol

The male-produced sex pheromone from the Brazilian rice stalk stink bug Tibraca limbativentris is reported. Olfactometer bioassays with sexually mature males and females showed that males attracted females, which suggests that males release a sex pheromone. Males were not attracted to either sex, nor were females attractive to conspecific females. Attraction of the females to males was highest at night. The headspace volatiles collected from male and female bugs were analyzed by gas chromatography (GC) and GC-mass spectrometry. Two male-specific compounds were identified as isomers of 1 'S'-zingiberenol, whereas a series of defensive compounds were identified in extracts from both sexes. Zingiberenol has three chiral centers, and the nonselective syntheses used produced two groups of isomers, zingiberenol I containing four isomers, namely (1RS,4RS, 1 'R)-4-( 1 ',5'-dimethylhex-4'-enyl)-1-methylcyclohex-2-en-1-ol, and zingiberenol II containing the other four isomers, namely (1RS,4RS,1'S)-4-(l',5'-dimethylhex-4'-enyl)-1-methylcyclohex-2-en-1-ol. Both groups of stereoisomers were more attractive than hexane controls. The absolute configuration of the insect-produced pheromonal components remains to be elucidated, but the 1'S' stereochemistry was established for at least one of the isomers.

Biotechnology, Biotechnologies, Microbiology, infectious diseases, Microbiologie, maladies infectieuses, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Microbiologie, Microbiology, Bactériologie, Bacteriology, Métabolisme. Enzymes, Metabolism. Enzymes, Bacteria, Bactérie, Acétate, Acetate, Acetato, Anaérobiose, Anaerobiosis, Cyanobacteria, Diholoside, Disaccharide, Diholosido, Ethanol, Etanol, Fermentation, Fermentación, Glycogène, Glycogen, Glicógeno, Lactate, Lactates, Lactato, Métabolisme, Metabolism, Metabolismo, Obscurité, Obscurity, Oscuridad, Sulfure, Sulfides, Sulfuro, Tréhalose, Trehalose, Trehalosa, Fermentation hétérolactique, and Oscillatoria limosa

The marine nitrogen-fixing cyanobacterium Oscillatoria limosa, strain 23 (Oldenburg) was investigated with respect to its dark anaerobic metabolism. As soon as the cells were incubated anaerobically in the dark, they started to ferment. Glycogen was presumably degraded via the heterolactic fermentative pathway. Glycogen-glucose was degraded to equimolar amounts of lactate, ethanol and carbon dioxide. The disaccharide trehalose, which serves as an osmoprotectant in O. limosa, was also catabolized.

Biotechnology, Biotechnologies, Microbiology, infectious diseases, Microbiologie, maladies infectieuses, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Microbiologie, Microbiology, Bactériologie, Bacteriology, Métabolisme. Enzymes, Metabolism. Enzymes, Bacteria, Cyanobacteria, Bactérie, Azote, Nitrogen, Nitrogeno, Aérobiose, Aerobiosis, Enzyme, Enzima, Fixation azote, Nitrogen fixation, Fijación nitrogeno, Lumière, Light, Luz, Métabolisme, Metabolism, Metabolismo, Nitrogenase, Obscurité, Obscurity, Oscuridad, Oscillatoria, Photosynthèse, Photosynthesis, Fotosíntesis, Respiration cellulaire, Cell respiration, and Respiración celular

Biotechnology, Biotechnologies, Microbiology, infectious diseases, Microbiologie, maladies infectieuses, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Microbiologie, Microbiology, Bactériologie, Bacteriology, Métabolisme. Enzymes, Metabolism. Enzymes, Biotechnologie, Biotechnology, Recherche fondamentale orientée, Mission oriented research, Biologie des microorganismes d'intérêt industriel confirmé ou potentiel, Biology of microorganisms of confirmed or potential industrial interest, Physiologie et métabolisme, Physiology and metabolism, Bacteria, Oscillatoriaceae, Oscillatoriales, Bactérie, Culture microorganisme, Microorganism culture, Cultivo microorganismo, Cyanobacteria, Enzyme, Enzima, Fixation azote, Nitrogen fixation, Fijacion nitrogenada, Nitrogenase, Oscillatoria, Oxidoreductase, Oxidorreductasa, Oxygène, Oxygen, Protection, Proteccion, Toxicité, Toxicity, and Toxicidad

Biotechnology, Biotechnologies, Microbiology, infectious diseases, Microbiologie, maladies infectieuses, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Microbiologie, Microbiology, Bactériologie, Bacteriology, Métabolisme. Enzymes, Metabolism. Enzymes, Biotechnologie, Biotechnology, Recherche fondamentale orientée, Mission oriented research, Biologie des microorganismes d'intérêt industriel confirmé ou potentiel, Biology of microorganisms of confirmed or potential industrial interest, Physiologie et métabolisme, Physiology and metabolism, Bacteria, Oscillatoriaceae, Oscillatoriales, Bactérie, Alternance, Alternancia, Culture microorganisme, Microorganism culture, Cultivo microorganismo, Cyanobacteria, Dosage, Assay, Dosificacion, Enzyme, Enzima, Fixation azote, Nitrogen fixation, Fijacion nitrogenada, Lumière, Light, Luz, Nitrogenase, Obscurité, Obscurity, Oscuridad, Oscillatoria, Oxidoreductase, and Oxidorreductasa

Marine biology, limnology, Biologie marine, limnologie, Ecology, Ecologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Ecologie animale, vegetale et microbienne, Animal, plant and microbial ecology, Ecologie microbienne, Microbial ecology, Milieux divers (espace extraatmosphérique, air, eau), Various environments (extraatmospheric space, air, water), Bacteria, Bactérie, Cyanobacteria, Eau mer, Seawater, Agua mar, Ecologie, Ecology, Ecologia, Fixation azote, Nitrogen fixation, Mer du Nord, North Sea, Nitrogenase, Zone intertidale, and Intertidal zone

Ecology, Ecologie, Environment, Environnement, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Ecologie animale, vegetale et microbienne, Animal, plant and microbial ecology, Ecologie animale et végétale, Animal and plant ecology, Autoécologie, Autoecology, Animaux, Animals, Protozoa. Invertebrata, Arthropoda, Communication chimique, Chemical communication, Comunicación química, Composé sémiochimique, Semiochemicals, Heteroptera, Insecta, Invertebrata, Analyse chimique, Chemical analysis, Análisis químico, Attractif, Attractant, Atractivo, Composé volatil, Volatile compound, Compuesto volátil, Pentatomidae, Phéromone sexuelle, Sex pheromone, Feromona sexual, Thyanta pallidovirens, Sex attractant pheromone, Thyanta accerra custator, methyl (E2,Z4,Z6)-decatrienoate, redundant, sesquiterpene, zingiberene β-sesquiphellandrene, and α-curcumene

The male-produced sex pheromone of the red-shouldered stink bug, Thyanta pallidovirens (Stål) (Hemiptera: Pentatomidae) consists of a blend of methyl (E2,Z4,Z6)-decatrienoate (E2,Z4,Z6-10:COOMe), and the sesquiterpenes (+)-α-curcumene, (-)-zingiberene, and (-)-β-sesquiphellandrene. In laboratory bioassays, sexually mature males attracted sexually mature females but not males, and females did not attract either sex. Extracts of volatiles collected from sexually mature males contained compounds not present in extracts from females or sexually immature males, and male-produced extract was attractive to females. Biological activity was lost when the extract was fractionated, indicating that the pheromone consisted of at least two components having different chemical, properties. Individually, pheromone components were not attractive to females, but E2,Z4,Z6-10:COOMe in combination with at least one of the three male-produced sesquiterpenes was attractive. The presence of more than one sesquiterpene in the blend did not increase attraction, indicating redundancy in the pheromone signal. Male extract was as attractive as a blend reconstructed from synthesized compounds, indicating all biologically active components had been identified. In bioassays conducted at dusk in a 1- x 1- x 1-m screen field cage, females were attracted to synthetic pheromone lures. In field trials, adult female T pallidovirens were attracted to pheromone-baited traps in relatively low numbers. The profile of volatiles released by sexually mature males of a congeneric species, Thyanta accerra custator McAtee, was remarkably similar to that of male T pallidovirens, with the exception that the former species produced (E)-2-decenal, a compound that was not found in T. pallidovirens extracts.