Growing interest in the effects of global change on the metabolism, stoichiometry and cycling of carbon in aquatic ecosystems has motivated research on the export of organic carbon (OCE) from ...catchments. In this article, quantitative and functional features of the annual export rates of total, particulate and dissolved organic carbon (TOC, POC and DOC) were reviewed, and the stoichiometry of export (OC:N, OC:P and N:P) from 550 catchments worldwide was reported. TOC export ranged 2.1–92,474 kg C km−2 year−1, POC export ranged 0.4–73,979 kg C km−2 year−1 and DOC export ranged 1.2–56,946 kg C km−2 year−1. Exports of TOC and DOC were strongly linked, but POC export was unrelated to DOC. The DOC fraction comprised on average 73 ± 21% of TOC export. The export rates of organic carbon were poorly related to those of total nitrogen and total phosphorus. Discrete and continuous environmental variables failed to predict TOC export, but DOC export was influenced by discharge and catchment area worldwide. Models of OCE in different catchment types were controlled by different environmental variables; hydrological variables were generally better predictors of OCE than anthropogenic and soil variables. Elemental ratios of carbon export in most catchments were above the Redfield ratio, suggesting that phosphorus may become the limiting nutrient for downstream plant growth. These ratios were marginally related to environmental data. More detailed hydrological data, consideration of in-stream processes and the use of quasi-empirical dynamical models are advocated to improve our knowledge of OCE rates and those of other nutrients.
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BFBNIB, DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NMLJ, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Metasurfaces and nanoantennas are redefining what can be achieved in terms of optical beam manipulation, as they provide a versatile design platform towards moulding the flow of light at will. Yet, ...once a conventional metasurface is designed and realised, its effect on optical beams is repeatable and stationary, thus its performance is 'locked-in' at the fabrication stage. A much wider range of applications, such as dynamic beam steering, reconfigurable and dynamic lensing, optical modulation and reconfigurable spectral filtering, could be achieved if real-time tuning of metasurface optical properties were possible. Chalcogenide phase-change materials, because of their rather unique ability to undergo abrupt, repeatable and non-volatile changes in optical properties when switched between their amorphous and crystalline phases, have in recent years been combined with metasurface architectures to provide a promising platform for the achievement of dynamic tunability. In this paper, the concept of dynamically tunable phase-change metasurfaces is introduced, and recent results spanning the electromagnetic spectrum from the visible right through to the THz regime are presented and discussed. The progress, potential applications, and possible future perspectives of phase-change metasurface technology are highlighted, and requirements for the successful implementation of real-world applications are discussed.
This study reviews nitrogen export rates from 946 rivers of the world to determine the influence of quantitative (runoff, rainfall, inhabitant density, catchment area, percentage of land use cover, ...airborne deposition, fertilizer input) and qualitative (dominant type of forest, occurrence of stagnant waterbodies, dominant land use, occurrence of point sources, runoff type) environmental factors on nitrogen fluxes. All fractions (total, nitrate, ammonia, dissolved organic and particulate organic) of nitrogen export showed a left-skewed distribution, which suggests a relatively pristine condition for most systems. Total nitrogen export showed the highest variability whereas total organic nitrogen export comprised the dominant fraction of export. Nitrogen export rates were only weakly explained by our qualitative and quantitative environmental variables. Our study suggests that the consideration of spatial and temporal scales is important for predicting nitrogen export rates using simple and easy-to-get environmental variables. Regionally based modelling approaches prove more useful than global-scale analyses.
Spatial and temporal scales are important determinants for nitrogen export from catchments and emphasis should be put on regional approaches.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Mammal inventories in tropical forests are often difficult to carry out, and many elusive species are missed or only reported from interviews with local people. Camera traps offer a new tool for ...conducting inventories of large- and medium-sized terrestrial mammals. We evaluated the efficiency of camera traps based on data from two surveys carried out at a single site during 2 consecutive years. The survey efforts were 1440 and 2340 camera days, and 75 and 86% of the 28 large- and medium-sized terrestrial mammal species known to occur at the site were recorded. Capture frequencies for different species were highly correlated between the surveys, and the capture probability for animals that passed in front of the cameras decreased with decreasing size of the species. Camera spacing and total survey area had little influence on the number of species recorded, with survey effort being the main factor determining the number of recorded species. Using a model we demonstrated the exponential increase in survey effort required to record the most elusive species. We evaluated the performance of different species richness estimators on this dataset and found the Jackknife estimators generally to perform best. We give recommendations on how to increase efficiency of camera trap surveys exclusively targeted at species inventories.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
•Results for three emulsification arrangements were linked using a Poisson chain model.•The model allowed for comparison in-between arrangements using in-line rotor-stators.•A simplification of the ...Poisson chain model for long times was proposed.•The simplified model explained kinetics and volume dependency for batch systems.•Modes were used as measure of central tendency due to the noise that bimodality produced.
In-line rotor-stator mixers are widely used to emulsify immiscible liquids, but there is little understanding on the size reduction kinetics and on their performance if used in a continuous or in a recycle arrangement. In this study, a systematic series of experiments were performed to study the droplet size reduction of a 10cSt silicon oil coarse emulsion using different flow rates and number of passes for a continuous and a recycle configuration using a L5M-A Silverson Laboratory mixer.
The droplets size distributions obtained were bimodal. It was found that the mode of the larger daughter droplets is a better parameter to follow the emulsification kinetics than the Sauter mean diameter; the volume fraction of the small daughter droplets was estimated to be ≈6% using two generalized gamma functions. For the continuous arrangement it was found that impeller speed and mean residence time inside the rotor-stator correlated with an average error of 3.2%. It was also found that a Poisson chain can link the results of both operation arrangements. This stochastic model allowed following the disappearance rate of the coarse droplets and the evolution of the daughter droplets’ mode with an average error of 2.3%. The model developed allowed the comparison of both arrangements using an in-line rotor-stator.
A simplification of the Poisson chain model for long times was used to analyse batch emulsification kinetics. The droplet size reduction rate and batch volume could be explained in terms of the in-line results.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Introduction
For many samples studied by GC-based metabolomics applications, extensive sample preparation involving extraction followed by a two-step derivatization procedure of methoximation and ...trimethylsilylation (TMS) is typically required to expand the metabolome coverage. Performing normalization is critical to correct for variations present in samples and any biases added during the sample preparation steps and analytical runs. Addressing the totality of variations with an adequate normalization method increases the reliability of the downstream data analysis and interpretation of the results.
Objectives
Normalizing to sample mass is one of the most commonly employed strategies, while the total peak area (TPA) as a normalization factor is also frequently used as a post-acquisition technique. Here, we present a new normalization approach, total derivatized peak area (TDPA), where data are normalized to the intensity of all derivatized compounds. TDPA relies on the benefits of silylation as a universal derivatization method for GC-based metabolomics studies.
Methods
Two sample classes consisting of systematically incremented sample mass were simulated, with the only difference between the groups being the added amino acid concentrations. The samples were TMS derivatized and analyzed using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC × GC-TOFMS). The performance of five normalization strategies (no normalization, normalized to sample mass, TPA, total useful peak area (TUPA), and TDPA) were evaluated on the acquired data.
Results
Of the five normalization techniques compared, TUPA and TDPA were the most effective. On PCA score space, they offered a clear separation between the two classes.
Conclusion
TUPA and TDPA carry different strengths: TUPA requires peak alignment across all samples, which depends upon the completion of the study, while TDPA is free from the requirement of alignment. The findings of the study would enhance the convenient and effective use of data normalization strategies and contribute to overcoming the data normalization challenges that currently exist in the metabolomics community.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•σ and π bands respond in the same way to the interferences (in the alkali/graphene system).•The charge is transferred from the adatom to graphene.•Interference effect make the alkali/graphene system ...behave as a weakly coupled one.
We present a theoretical study of the localized aspects of the alkali-metal atoms (Li, Na, K) interacting with graphene. We use an ab-initio calculation of the Hamiltonian parameters where the chemical properties of the interacting atoms (alkali and C), and the extended features of the electronic band structure of the solid are considered. Adatoms with a s-type valence orbital where the electron repulsion (U) in the atom assumes a finite value are considered. Three possible configuration states are analyzed: zero, one (spin up or down), and two electrons in the valence state. We describe the surface-atom interaction by projecting the Anderson Hamiltonian on the subspace of these atomic configurations, and introduced the Green's functions required to calculate the magnitudes of interest. Physical quantities of interest such as hybridization function, the adatom spectral density and transferred charge are obtained. We find that the interaction of alkali-metal atoms with graphene involves several atoms of the solid due to the extension of the s-type alkali atomic state and C atomic states. Charge is mostly transferred from the adatom towards the graphene sheet.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The DNA vaccine, AV-1959D, targeting N-terminal epitope of Aβ peptide, has been proven immunogenic in mice, rabbits, and non-human primates, while its therapeutic efficacy has been shown in mouse ...models of Alzheimer's disease (AD). Here we report for the first time on IND-enabling biodistribution and safety/toxicology studies of cGMP-grade AV-1959D vaccine in the Tg2576 mouse model of AD. We also tested acute neuropathology safety profiles of AV-1959D in another AD disease model, Tg-SwDI mice with established vascular and parenchymal Aβ pathology in a pre-clinical translational study. Biodistribution studies two days after the injection demonstrated high copy numbers of AV-1959D plasmid after single immunization of Tg2576 mice at the injection sites but not in the tissues of distant organs. Plasmids persisted at the injection sites of some mice 60 days after vaccination. In Tg2576 mice with established amyloid pathology, we did not observe short- or long-term toxicities after multiple immunizations with three doses of AV-1959D. Assessment of the repeated dose acute safety of AV-1959D in cerebral amyloid angiopathy (CAA) prone Tg-SwDI mice did not reveal any immunotherapy-induced vasogenic edema detected by magnetic resonance imaging (MRI) or increased microhemorrhages. Multiple immunizations of Tg-SwDI mice with AV-1959D did not induce T and B cell infiltration, glial activation, vascular deposition of Aβ, or neuronal degeneration (necrosis and apoptosis) greater than that in the control group determined by immunohistochemistry of brain tissues. Taken together, the safety data from two different mouse models of AD substantiate a favorable safety profile of the cGMP grade AV-1959D vaccine supporting its progression to first-in-human clinical trials.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Most studies dealing with mycorrhizal associations and drought have focused on the plants, not on the fungi, and tolerance and adaptations of arbuscular mycorrhizal (AM) fungi to cope with water ...stress are virtually unknown. This study was conducted to assess how water stress directly affects an AM fungus isolate, particularly through morphological and physiological changes in the external mycelium. We used two-compartment pots separated by mesh and an air gap that allowed us to apply water stress treatments only to the external mycelium. Clover (
Trifolium subterraneum
L.) plants inoculated with
Rhizophagus intraradices
grew at high humidity until external mycorrhizal mycelium developed in the mycelium compartment. Then, we started three watering treatments: high (H, 70% of soil water holding capacity), low (L, 10%), and mixed watering (HLHL, 70–10–70-10%) only in the hyphal compartment. The HLHL treatment was rewetted once to 70% after 42 days. We measured total mycelium length, hyphal length in diameter categories, respiration activity, and protoplasm fragmentation 42 and 76 days after starting the treatments.
Rhizophagus intraradices
mycelium responded to water stress by reducing its length, maintaining larger diameter hyphae, and concentrating protoplasm activity in fragments in the HLHL and L treatments. In both water stress treatments, changes suggested a trade-off between avoiding desiccation and storing resources, and maintaining soil exploration and water uptake capacity.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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