Marine microalgae sequester as much CO₂ into carbohydrates as terrestrial plants. Polymeric carbohydrates (i.e., glycans) provide carbon for heterotrophic organisms and constitute a carbon sink in ...the global oceans. The quantitative contributions of different algal glycans to cycling and sequestration of carbon remain unknown, partly because of the analytical challenge to quantify glycans in complex biological matrices. Here, we quantified a glycan structural type using a recently developed biocatalytic strategy, which involves laminarinase enzymes that specifically cleave the algal glycan laminarin into readily analyzable fragments. We measured laminarin along transects in the Arctic, Atlantic, and Pacific oceans and during three time series in the North Sea. These data revealed a median of 26 ± 17% laminarin within the particulate organic carbon pool. The observed correlation between chlorophyll and laminarin suggests an annual production of algal laminarin of 12 ± 8 gigatons: that is, approximately three times the annual atmospheric carbon dioxide increase by fossil fuel burning. Moreover, our data revealed that laminarin accounted for up to 50% of organic carbon in sinking diatom-containing particles, thus substantially contributing to carbon export from surface waters. Spatially and temporally variable laminarin concentrations in the sunlit ocean are driven by light availability. Collectively, these observations highlight the prominent ecological role and biogeochemical function of laminarin in oceanic carbon export and energy flow to higher trophic levels.
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Parkinson's disease (PD) and Multiple System Atrophy (MSA) are clinically distinctive diseases that feature a common neuropathological hallmark of aggregated α-synuclein. Little is known about how ...differences in α-synuclein aggregate structure affect disease phenotype. Here, we amplified α-synuclein aggregates from PD and MSA brain extracts and analyzed the conformational properties using fluorescent probes, NMR spectroscopy and electron paramagnetic resonance. We also generated and analyzed several in vitro α-synuclein polymorphs. We found that brain-derived α-synuclein fibrils were structurally different to all of the in vitro polymorphs analyzed. Importantly, there was a greater structural heterogeneity among α-synuclein fibrils from the PD brain compared to those from the MSA brain, possibly reflecting on the greater variability of disease phenotypes evident in PD. Our findings have significant ramifications for the use of non-brain-derived α-synuclein fibrils in PD and MSA studies, and raise important questions regarding the one disease-one strain hypothesis in the study of α-synucleinopathies.
Potassium chloride (KCl) and magnesium chloride (MgCl2) can be used to reduce carbon dioxide (CO2) and nitrous oxide (N2O) emissions, but their efficacy can be strongly affected by their Cl− ...concentration. This study aimed to compare the behaviour of different Cl− salts and concentrations with that of a typical commercial nitrification inhibitor (3, 4‐dimethylpyrazole phosphate, PIADIN). KCl, MgCl2 and PIADIN were investigated under a laboratory incubation experiment for two months. KCl and MgCl2 were applied at 0.5 and 1.0 g kg−1, while PIADIN was applied at 25 mg kg−1 soil. CO2 and N2O concentrations were analysed during the incubation period. The NH4+ and NO3‐ dynamics in soil were also measured. The results showed 0.5 and 1.0 g kg−1 KCl and 0.5 g kg−1 MgCl2 decreased CO2‐C emissions by 43%–46% and increased N2O‐N emissions by 15%–48%, whereas 1.0 g kg−1 MgCl2 decreased CO2‐C emissions by 72% and N2O‐N emissions by 19%. KCl and MgCl2 retarded the decrease of the NH4+‐N concentration and increase of the NO3‐‐N concentration. PIADIN reduced the emissions of CO2‐C by 113% and N2O‐N by 97% and maintained a high soil NH4+‐N concentration and low NO3‐‐N concentration. MgCl2 addition at 1.0 g kg−1 was an effective treatment as the Mg both fertilized the soil and inhibited CO2‐C and N2O‐N emissions. Moreover, 1.0 g kg−1 MgCl2 could retard soil nitrification, the decrease of NH4+‐N concentration and the increase of NO3‐‐N concentration. While PIADIN had no fertilizing value, it was a more effective nitrification inhibitor than Cl− salts.
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Part of vehicle interior noise is caused by the complex turbulent flow field behind the a-pillar and side mirror. It excites the structure of the side window, which radiates noise into the interior. ...Both aerodynamic pressure excitation and acoustic sound sources in the flow play an important role. In this work, the influence of both excitation mechanisms is investigated numerically in a hybrid simulation on a simplified car geometry. The generic model allows for an exact definition of boundary conditions and good reproducibility of simulation results. An incompressible Large-Eddy-Simulation (LES) of the flow is conducted, from which acoustic source terms within the flow field and transient fluid forces acting on the surface of the side window are extracted. This data is used in a coupled vibroacoustic and aeroacoustic simulation of the structure and passenger cabin of the vehicle. A finite element (FE) approach is used for the simulations and detailed modeling of the structure and the influence of interior absorption properties is emphasized. The computed excitation on the side window and the interior noise levels are successfully validated by using experimental data. The importance and contribution of both aerodynamic and acoustic pressure excitation to the interior sound level are determined.
The number of operations of Unmanned Aerial Vehicles (UAV), commonly referred to as “drones”, has strongly increased in the past and is likely to further grow in the future. Therefore, drones are ...becoming a growing new source of environmental noise pollution, and annoyance reactions to drone noise are likely to occur in an increasing share of the population. To date, research on drone noise emission characteristics, and in particular also on health impacts, seems scarce, but systematic overviews on these topics are missing. The objective of this study was to establish a systematic literature review on drone noise emissions and noise effects on humans. The paper presents the methodology of the systematic reviews performed separately for noise emission and noise effects, assembles current literature, gives an overview on the state of knowledge, and identifies research gaps. Current literature suggests that drone noise is substantially more annoying than road traffic or aircraft noise due to special acoustic characteristics such as pure tones and high-frequency broadband noise. A range of open questions remains to be tackled by future studies.
Background
Nitrification inhibitors (NI) may be used to inhibit nitrous oxide (N2O) emissions from agricultural soils, but their efficacy could be strongly affected by soil temperature and moisture.
...Aims
This study investigated how different NI behave in a sandy soil under variable temperature and moisture levels, which currently remains unclear.
Methods
Efficacies of four NI dicyandiamide (DCD), 3,4‐dimethylpyrazole phosphate (DMPP), nitrogenous mineral fertilizers containing the DMPP ammonium stabilizer (ENTEC) and active ingredients: 3.00–3.25% 1,2,4‐triazole and 1.50–1.65% 3‐methylpyrazole (PIADIN) were investigated in an incubation experiment under two soil temperatures (15 and 25°C) and two moisture levels 60% and 80% water‐holding capacity (WH) for 60 days in a sandy soil. The soil received 0.5 g NH4+‐N kg−1 soil and the inhibitors were applied at 5% of applied N. Total N2O emissions were calculated based on gas samples collected throughout the incubation period.
Results
Increasing soil temperature from 15 to 25°C decreased N2O emissions by 73–191% while increasing soil moisture from 60% to 80% WHC caused a 109–251% increase in the emissions. ENTEC followed by DCD were the least effective inhibitors to reduce N2O emissions under all temperature and moisture combinations. Depending upon temperature and soil moisture, DMPP and PIADIN inhibited 85–100% of N2O emissions. At 15°C, both DMPP and PIADIN almost completely inhibited N2O emissions. At 25°C, the efficacy of PIADIN decreased to 88%, while that of DMPP ranged from 86% to 98%. Increased soil moisture content improved the efficacy of all the NI.
Conclusions
Overall, DMPP and PIADIN were more effective than DCD in a sandy soil under both the soil moisture levels and temperatures. DMPP was the most effective inhibitor, completely inhibiting N2O emissions at 15–25°C and up to 80% WHC in this soil, and is therefore recommended for use in agricultural lands. The concentration of the NI contained in ENTEC was insufficient to affect nitrification at the both soil moisture levels and temperatures.
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The voltage-dependent anion channel (VDAC), also known as mitochondrial porin, is the most abundant protein in the mitochondrial outer membrane (MOM). VDAC is the channel known to guide the metabolic ...flux across the MOM and plays a key role in mitochondrially induced apoptosis. Here, we present the 3D structure of human VDAC1, which was solved conjointly by NMR spectroscopy and x-ray crystallography. Human VDAC1 (hVDAC1) adopts a β-barrel architecture composed of 19 β-strands with an α-helix located horizontally midway within the pore. Bioinformatic analysis indicates that this channel architecture is common to all VDAC proteins and is adopted by the general import pore TOM40 of mammals, which is also located in the MOM.
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Pathogenic bacteria using a type III secretion system (T3SS) to manipulate host cells cause many different infections including Shigella dysentery, typhoid fever, enterohaemorrhagic colitis and ...bubonic plague. An essential part of the T3SS is a hollow needle-like protein filament through which effector proteins are injected into eukaryotic host cells. Currently, the three-dimensional structure of the needle is unknown because it is not amenable to X-ray crystallography and solution NMR, as a result of its inherent non-crystallinity and insolubility. Cryo-electron microscopy combined with crystal or solution NMR subunit structures has recently provided a powerful hybrid approach for studying supramolecular assemblies, resulting in low-resolution and medium-resolution models. However, such approaches cannot deliver atomic details, especially of the crucial subunit-subunit interfaces, because of the limited cryo-electron microscopic resolution obtained in these studies. Here we report an alternative approach combining recombinant wild-type needle production, solid-state NMR, electron microscopy and Rosetta modelling to reveal the supramolecular interfaces and ultimately the complete atomic structure of the Salmonella typhimurium T3SS needle. We show that the 80-residue subunits form a right-handed helical assembly with roughly 11 subunits per two turns, similar to that of the flagellar filament of S. typhimurium. In contrast to established models of the needle in which the amino terminus of the protein subunit was assumed to be α-helical and positioned inside the needle, our model reveals an extended amino-terminal domain that is positioned on the surface of the needle, while the highly conserved carboxy terminus points towards the lumen.
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DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this study the influence of polycarboxylate-based polyelectrolytes on the particle interaction among tricalcium silicate (C
3S, main clinker phase), calcium silicate hydrates (C
S
H), and calcium ...aluminate sulfate hydrates (ettringite) (main hydration phases) has been examined. These phases are the constituents of major concern during early hydration of cement suspensions. The results of zeta potential measurements on single mineral phase experiments show that the phases C
3S and C
S
H are positively charged in synthetic pore solution (liquid phase of hydrating cement suspension), whereas the ettringite is negatively charged. Due to these opposite charges, ettringite crystals should coagulate with C
S
H phases and/or deposit on surfaces of the much larger C
3S clinker particles. This behavior was proven by cryo-microscopic analysis of high-pressure frozen cement suspensions, which illustrates the consequences of colloidal mechanisms on the microstructure of early cement suspensions. Furthermore, it is shown that the polyelectrolytes have a much higher adsorption affinity to ettringite surfaces (hydrate phase) compared to silicate surfaces. However, the results from rheology experiments reveal that the presence of polyelectrolytes has a strong impact on the suspension properties of all investigated mineral phases by decreasing yield stress and plastic viscosity. From the results it can be concluded that the ettringite is the dominant mineral phase in terms of the state of dispersion which includes particle–particle and particle–polyelectrolyte interaction in the bulk cement system.
The zeta potential of the ettringite phase dominates the zeta potential of the bulk cement suspension. The ettringite crystals are either attached on clinker particle surfaces (light blue) or tend to be dispersed (dark blue) in the pore solution in the presence of an anionic polymer.
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