Increase in the oxygen concentration in Amazon waters resulting from the root exudation of two notorious water plants, Eichhornia crassipes (Pontederiaceae) and Pistia stratiotes (Araceae)

Qualitative and quantitative analyses were carried out to determine the amount of oxygen that enters the water through the root systems of two floating Neotropical plants, Eichhornia crassipes and Pistia stratiotes, under nearly anaerobic conditions. The physiological analyses were supplemented by anatomical investigations. A measurable oxygen input from both plants was detected: that from E. crassipes was 116 mg O2 * h-1 * m-2, and from P. stratiotes, 58 mg O2 * h-1 * m-2. Water surface area representing 4 kg and 2.9 kg fresh weight, respectively. The O2 input from E. crassipes seemed to be independent of the amount of photosynthesis, suggesting that a pressure ventilation was responsible for the input. In the case of P. stratiotes, a relationship was found between the photosynthetic activity and the O2 input. The significance of this input for the Neotropical ecosystem and the fish fauna is discussed

Inlet conditions for large eddy simulation of gas-turbine swirl injectors

Copyright © 2008 American Institute of Aeronautics and AstronauticsIn this paper, we present a novel technique for generating swirl inlets for large eddy simulation. The velocity a short distance downstream of the inlet to the main domain is sampled and the flow velocity data are reintroduced back into the domain inlet, creating an inlet section integrated into the main domain in which turbulence can develop. Additionally, variable artificial body forces and velocity corrections are imposed in this inlet section, with feedback control to force the flow toward desired swirl, mean, and turbulent profiles. The method was applied to flow in an axisymmetric sudden expansion, with and without swirl at the inlet, and compared against experimental and literature large eddy simulation data and against similar results in the literature. The method generates excellent results for this case and is elegant and straightforward to implement

Ecological and physiological investigations on Eichhornia crassipes (MART.) SOLMS. 1. The effect of different environmental conditions on the development of root colour

The cell walls of E. crassipes roots show areas of strong coloration, which can range from light brown through brown, blue, violet to blue-black, while the plants appear generally healthy. This work describes the environmental factors which control the particularly noticeable blue colouration of the roots. From studies conducted under defined conditions in growth chambers, substrate nitrogen deficiency in the light produces an intense blue root colouration. Thus with nitrate or ammonium deficiency of the nutrient medium E. crassipes can be considered a nitrogen monitor

Measurement of the 187Re({\alpha},n)190Ir reaction cross section at sub-Coulomb energies using the Cologne Clover Counting Setup

Uncertainties in adopted models of particle+nucleus optical-model potentials directly influence the accuracy in the theoretical predictions of reaction rates as they are needed for reaction-network calculations in, for instance, {\gamma}-process nucleosynthesis. The improvement of the {\alpha}+nucleus optical-model potential is hampered by the lack of experimental data at astrophysically relevant energies especially for heavier nuclei. Measuring the Re187({\alpha},n)Ir190 reaction cross section at sub-Coulomb energies extends the scarce experimental data available in this mass region and helps understanding the energy dependence of the imaginary part of the {\alpha}+nucleus optical-model potential at low energies. Applying the activation method, after the irradiation of natural rhenium targets with {\alpha}-particle energies of 12.4 to 14.1 MeV, the reaction yield and thus the reaction cross section were determined via {\gamma}-ray spectroscopy by using the Cologne Clover Counting Setup and the method of {\gamma}{\gamma} coincidences. Cross-section values at five energies close to the astrophysically relevant energy region were measured. Statistical model calculations revealed discrepancies between the experimental values and predictions based on widely used {\alpha}+nucleus optical-model potentials. However, an excellent reproduction of the measured cross-section values could be achieved from calculations based on the so-called Sauerwein-Rauscher {\alpha}+nucleus optical-model potential. The results obtained indicate that the energy dependence of the imaginary part of the {\alpha}+nucleus optical-model potential can be described by an exponential decrease. Successful reproductions of measured cross sections at low energies for {\alpha}-induced reactions in the mass range 141{\leq}A{\leq}187 confirm the global character of the Sauerwein-Rauscher potential

Instabilitäten von Infiltrationsfronten verursacht durch langzeitige Bewässerung mit behandelten Abwässern

Die Bewässerung von Agrarflächen mit behandelten Abwässern (TWW) ist eine weitverbreitete Praxis in ariden und semi-ariden Gebieten. In Israel liegt auf dieser Wasserressource ein besonderer Fokus, da Abwässer ganzjährig verfügbar sind, Frischwasserressourcen schonen und einen wichtigen Beitrag zur Wiederverwendung von Nährstoffen leisten. Vorangegangene Studien haben gezeigt, dass organische Stoffe die Benetzbarkeit von Mineraloberflächen beeinträchtigen und die Bodenstruktur verändern können. Auf Grund der erhöhten Restmenge an organischen Bestandteilen im TWW kann eine langzeitige Bewässerung im Boden zu Veränderungen der Struktur, Hydrophobizität, präferentiellen Fließwegen und dem Auswaschen von Pflanzenschutzmitteln und Nährstoffen führen. In dieser Studie wurden (i) eine neue Methode zur Quantifizierung von Wassergehaltsänderungen in ungestörten Bodenproben via Radiographie entwickelt und (ii) Instabilitäten von Infiltrationsfronten in Böden, die seit über zwanzig Jahren mit TWW bewässert wurden, detektiert. Wir untersuchten ungestörte Bodenproben von zwei Obstplantagen in Israel mit langzeitiger TWW-Bewässerung, wobei an einem Standort zusätzlich ein Teil mit Frischwasser bewässert wird. Die Proben umfassen zwei unterschiedliche Bodentexturen und zwei unterschiedliche Bewässerungsverfahren: Frischwasser und TWW. Des Weiteren wurden saisonale Abhängigkeiten (Trocken-/ Regenzeit) mit in die Studie eingeschlossen um die Persistenz der Effekte zu erfassen. Ungestörte, zylindrische Bodenproben wurden aus dem Oberboden (0-20 cm) genommen und Bewässerungsversuche innerhalb eines Röntgensystems durchgeführt. Durch Bildanalyse konnten die Ausbreitung der Infiltrationsfronten und räumliche Wassergehaltsänderungen als Funktion der Zeit erfasst werden. Die Versuche wurden mit unterschiedlichen Anfangswassergehalten wiederholt. In dieser Studie konnte gezeigt werden, dass die Stabilität der Infiltrationsfronten in diesen Böden von der Wasserqualität und dem initialen Wassergehalt abgängig sind. Darüber hinaus konnte dargelegt werden, dass langzeitige TWW-Bewässerung zu einer persistenten Veränderung der Benetzbarkeit führen kann, unabhängig von der Saison. Diese Studie liefert einen experimentellen Nachweis über die Notwendigkeit von optimiertem Bewässerungsmanagement um präferentielles Wasserfließen zu vermeiden

The role of alanine and aspartate aminotransferases in C₄ photosynthesis

Schlüter U, Bräutigam A, Droz J‐M, Schwender J, Weber APM. The role of alanine and aspartate aminotransferases in C<sub>4</sub> photosynthesis. Plant Biology. 2019;21(S1):64-76.• Alanine and aspartate are essential transfer metabolites for C4 species of the NADmalic enzyme and phosphoenolpyruvate carboxykinase subtype. To some degree both amino acids are also part of the metabolite shuttle in NADP-malic enzyme plants. In comparison with C3 species, the majority of C4 species are therefore characterised by enhanced expression and activity of alanine and aspartate aminotransferases (AT) in the photosynthetically active tissue. Both enzymes exist in multiple copies and have been found in different subcellular compartments. We tested whether different C4 species show preferential recruitment of enzymes from specific lineages and subcellular compartments. • Phylogenetic analysis of alanine and aspartate ATs from a variety of monocot and eudicot C4 species and their C3 relatives was combined with subcellular prediction tools and analysis of the subsequent transcript amounts in mature leaves. • Recruitment of aspartate AT from a specific subcellular compartment was strongly connected to the biochemical subtype. Deviation from the main model was however observed in Gynandropsis gynandra. The configuration of alanine AT generally differed in monocot and eudicot species. C4 monocots recruited an alanine AT from a specific cytosolic branch, but eudicots use alanine AT copies from a mitochondrial branch. • Generally, plants display high plasticity in the setup of the C4 pathway. Beside the common models for the different C4 subtypes, individual solutions were found for plant groups or lineages

Deeply sequenced metagenome and metatranscriptome of a biogas-producing microbial community from an agricultural production-scale biogas plant

Bremges A, Maus I, Belmann P, et al. Deeply sequenced metagenome and metatranscriptome of a biogas-producing microbial community from an agricultural production-scale biogas plant. GigaScience. 2015;4(1): 33.Background The production of biogas takes place under anaerobic conditions and involves microbial decomposition of organic matter. Most of the participating microbes are still unknown and non-cultivable. Accordingly, shotgun metagenome sequencing currently is the method of choice to obtain insights into community composition and the genetic repertoire. Findings Here, we report on the deeply sequenced metagenome and metatranscriptome of a complex biogas-producing microbial community from an agricultural production-scale biogas plant. We assembled the metagenome and, as an example application, show that we reconstructed most genes involved in the methane metabolism, a key pathway involving methanogenesis performed by methanogenic Archaea. This result indicates that there is sufficient sequencing coverage for most downstream analyses. Conclusions Sequenced at least one order of magnitude deeper than previous studies, our metagenome data will enable new insights into community composition and the genetic potential of important community members. Moreover, mapping of transcripts to reconstructed genome sequences will enable the identification of active metabolic pathways in target organisms

Peer Reporting and the Perception of Fairness

Economic motives are not the only reasons for committing a (small) crime. People consider social norms and perceptions of fairness before judging a situation and acting upon it. If someone takes a bundle of printing paper from the office for private use at home, then a colleague who sees this can take action by talking to the offender or someone else (peer reporting). We investigate how fairness perception influences the decision to act upon incorrect behavior or not