The role of diverse soil microbiota in restoring erosion-induced degraded lands is well recognized. Yet, the facilitative interactions among symbiotic arbuscular mycorrhizal (AM) fungi, rhizobia, and heterotrophic bacteria, which underpin multiple functions in eroded ecosystems, remain unclear. Here, we utilized quantitative microbiota profiling and ecological network analyses to explore the interplay between the diversity and biotic associations of root-associated microbiota and multifunctionality across an eroded slope of a Robinia pseudoacacia plantation on the Loess Plateau. We found explicit variations in slope multifunctionality across different slope positions, associated with shifts in limiting resources, including soil phosphorus (P) and moisture. To cope with P limitation, AM fungi were recruited by R. pseudoacacia, assuming pivotal roles as keystones and connectors within cross-kingdom networks. Furthermore, AM fungi facilitated the assembly and composition of bacterial and rhizobial communities, collectively driving slope multifunctionality. The symbiotic association among R. pseudoacacia, AM fungi, and rhizobia promoted slope multifunctionality through enhanced decomposition of recalcitrant compounds, improved P mineralization potential, and optimized microbial metabolism. Overall, our findings highlight the crucial role of AM fungal-centered microbiota associated with R. pseudoacacia in functional delivery within eroded landscapes, providing valuable insights for the sustainable restoration of degraded ecosystems in erosion-prone regions.
Weniger anzeigenPitted impact deposits on Vesta show higher reflectance and pyroxene absorption band strengths compared to their immediate surroundings and other typical Vestan materials. We investigated whether heating to different temperatures for different durations of Vestan regolith analog materials can reproduce these spectral characteristics using mixtures of HEDs, the carbonaceous chondrite Murchison, and terrestrial analogs. We find no consistent spectral trend due merely to temperature increases, but observed that the interiors of many heated samples show both higher reflectance and pyroxene band I strength than their heated surfaces. With electron probe microanalysis, we additionally observe the formation of hematite, which could account for the higher reflectance. The presence of hematite indicates oxidation occurring in the sample interiors. In combination with heat, this might cause the increase of pyroxene band strengths through migration of iron cations. The effect grows larger with increasing temperature and duration, although temperature appears to play the more dominant role. A higher proportion of Murchison or the terrestrial carbonaceous chondrite analog within our mixtures also appears to facilitate the onset of oxidation. Our observations suggest that both the introduction of exogenic material on Vesta as well as the heating from impacts were necessary to enable the process (possibly oxidation) causing the observed spectral changes.
Weniger anzeigenConcrete symbols (e.g., sun, run) can be learned in the context of objects and actions, thereby grounding their meaning in the world. However, it is controversial whether a comparable avenue to semantic learning exists for abstract symbols (e.g., democracy). When we simulated the putative brain mechanisms of conceptual/semantic grounding using brain-constrained deep neural networks, the learning of instances of concrete concepts outside of language contexts led to robust neural circuits generating substantial and prolonged activations. In contrast, the learning of instances of abstract concepts yielded much reduced and only short-lived activity. Crucially, when conceptual instances were learned in the context of wordforms, circuit activations became robust and long-lasting for both concrete and abstract meanings. These results indicate that, although the neural correlates of concrete conceptual representations can be built from grounding experiences alone, abstract concept formation at the neurobiological level is enabled by and requires the correlated presence of linguistic forms.
Weniger anzeigenNanoporous gold (npAu) was tested as a catalyst for oxidations of various benzylic sp3-carbon positions in 9H-fluorene derivatives and similar hydrocarbons using tertbutyl hydroperoxide (TBHP) as an oxidant. The silver content in the npAu catalyst had a major influence on the overall conversion: Lower silver amounts (0.53 mol%) led to higher conversions, whereas higher amounts of silver increasingly resulted in the disproportionation of TBHP as a competing reaction. Because residual silver from the bulk alloy was oxidized by TBHP and leached into the solution during the reaction, the Ag content diminished over time. Therefore, the recycling of the catalyst had a positive effect on the conversion after each use. Using electron paramagnetic resonance (EPR) spectroscopy, the formation of radicals from TBHP by npAu was evidenced indicating a radical-based reaction mechanism which was further elucidated by NMR spectroscopic and GC-MS (trace) product analysis. Subsequent oxidations of benzylic sp3-carbon positions gave good to excellent conversions and chemoselectivities featuring npAu as a suitable catalyst for such reactions.
Weniger anzeigenPeople have a need to form and maintain fulfilling social contact, yet they differ with respect to with whom they satisfy the need and how quickly this need is deprived or overly satiated. These social dynamics across relationships and across time are theoretically delineated in the current article. Furthermore, we developed a questionnaire to measure individual differences in three aspects of such social dynamics: (a) Family-friends interdependence, (b) Social deprivation, and (c) Social oversatiation. In a longitudinal study spanning 9 weeks in spring 2020, in total 471 participants (18–75 years, 47% women) answered the newly developed items on social dynamics, questionnaires on social dispositions (e.g., affiliation motive, need to be alone, social anxiety), and questions on personal and indirect contact with family and friends during nationwide contact restrictions related to COVID-19. The results showed that individual differences in Family-friends interdependence, Social deprivation, and Social oversatiation can be measured reliably, validly, and with predictive value for changes in daily contact as contact restrictions were loosened. We discuss potential applications of the Social Dynamics Scale (SDS) for studying social relationships in healthy and clinical populations, and conclude that the brief self-report questionnaire of social dynamics can be useful for situations and samples where direct behavioral observations are not feasible.
Weniger anzeigenInteractions between membranes and biomolecular condensates can give rise to complex phenomena such as wetting transitions, mutual remodeling, and endocytosis. In this study, light-triggered manipulation of condensate engulfment is demonstrated using giant vesicles containing photoswitchable lipids. UV irradiation increases the membrane area, which can be stored in nanotubes. When in contact with a condensate droplet, the UV light triggers rapid condensate endocytosis, which can be reverted by blue light. The affinity of the protein-rich condensates to the membrane and the reversibility of the engulfment processes is quantified from confocal microscopy images. The degree of photo-induced engulfment, whether partial or complete, depends on the vesicle excess area and the relative sizes of vesicles and condensates. Theoretical estimates suggest that utilizing the light-induced excess area to increase the vesicle-condensate adhesion interface is energetically more favorable than the energy gain from folding the membrane into invaginations and tubes. The overall findings demonstrate that membrane-condensate interactions can be easily and quickly modulated via light, providing a versatile system for building platforms to control cellular events and design intelligent drug delivery systems for cell repair.
Weniger anzeigenGlycosaminoglycans (GAGs) are linear and acidic polysaccharides. They are ubiquitous molecules, which are involved in a wide range of biological processes. Despite being structurally simple at first glance, with a repeating backbone of alternating hexuronic acid and hexosamine dimers, GAGs display a highly complex structure, which predominantly results from their heterogeneous sulfation patterns. The commonly applied method for compositional analysis of all GAGs is "disaccharide analysis." In this process, GAGs are enzymatically depolymerized into disaccharides, derivatized with a fluorescent label, and then analysed through liquid chromatography. The limiting factor in the high throughput analysis of GAG disaccharides is the time-consuming liquid chromatography. To address this limitation, we here utilized trapped ion mobility-mass spectrometry (TIM-MS) for the separation of isomeric GAG disaccharides, which reduces the measurement time from hours to a few minutes. A full set of disaccharides comprises twelve structures, with eight possessing isomers. Most disaccharides cannot be differentiated by TIM-MS in underivatized form. Therefore, we developed chemical modifications to reduce sample complexity and enhance differentiability. Quantification is performed using stable isotope labelled standards, which are easily available due to the nature of the performed modifications.
Weniger anzeigenLewis acidic boron compounds are ubiquitous in chemistry due to their numerous applications, yet tuning and optimizing their properties towards different purposes is still a challenging field of research. In this work, the boron Lewis acid B[OTeF3(C6F5)2]3 was synthesized by reaction of the teflate derivative HOTeF3(C6F5)2 with BCl3 or BCl3·SMe2. This new compound presents a remarkably high thermal stability up to 300 °C, as well as one of the most sterically encumbered boron centres known in the literature. Theoretical and experimental methods revealed that B[OTeF3(C6F5)2]3 exhibits a comparable Lewis acidity to that of the well-known B(C6F5)3 and around 85% of the Lewis acidity of the related B(OTeF5)3. The affinity of B[OTeF3(C6F5)2]3 towards pyridine was accessed by Isothermal Titration Calorimetry (ITC) and compared to that of B(OTeF5)3 and B(C6F5)3. The ligand-transfer reactivity of this new boron compound towards different fluorides was demonstrated by the formation of an anionic Au(III) complex and a hypervalent iodine(III) species.
Weniger anzeigenThe molecular IrF5−, IrF6− anions and M[IrF6] (M = Na-Cs) ion pairs were prepared by co-deposition of laser-ablated MF with IrF6 and isolated in solid Ne or Ar matrices. The free anions were obtained by co-deposition of IrF6 with laser-ablated metals (Ir, Pt) as electron sources. The products were characterized in a combined analysis of matrix IR spectroscopy and electronic structure calculations using two-component quasi-relativistic DFT methods accounting for scalar-relativistic and spin-orbit coupling effects as well as multi-reference configuration-interaction approaches with SOC. Inclusion of SOC is crucial in the prediction of spectra and properties of IrF6− and its alkali-metal ion pairs. The observed IR bands and the computations show that the IrF6− anion adopts an Oh structure in a nondegenerate ground state stabilized by SOC effects, and not a distorted D4h structure in a triplet ground state as suggested by scalar-relativistic calculations. The corresponding “closed-shell” M[IrF6] ion pairs with C3v symmetry are stabilized by coordination of an alkali metal ion to three F atoms, and their structural change in the series from M = Na to Cs was proven spectroscopically. There is no evidence for the formation of IrF7, IrF7− or M[IrF7] (M = Na-Cs) ion pairs in our experiments.
Weniger anzeigenThe trifluorosilylarsinidene F3SiAs in the triplet ground state has been generated through the reaction of laser-ablated silicon atoms with AsF3 in cryogenic Ne- and Ar-matrices. The reactions proceed with the initial formation perfluorinated arsasilene FAsSiF2 in the singlet ground state by two As‒F bonds insertion reaction on annealing. The trifluorosilylarsinidene F3SiAs was formed via F-migration reactions of FAsSiF2 under irradiation at UV light (λ = 275 nm). The characterization of FAsSiF2 and F3SiAs by IR matrix-isolation spectroscopy is supported by computations at CCSD(T)-F12/aug-cc-pVTZ and B3LYP/aug-cc-pVTZ levels of theory.
Weniger anzeigenHerein we report a general access to silver(i) perfluoroalcoholates, their structure in the solid state and in solution, and their use as transfer reagents. The silver(i) perfluoroalcoholates are prepared by the reaction of AgF with the corresponding perfluorinated carbonyl compounds in acetonitrile and are stable for a prolonged time at –18 °C. X-Ray analysis of single crystals of perfluoroalcoholate species showed that two Ag(i) centers are bridged by the alcoholate ligands. In acetonitrile solution, Ag[OCF3] forms different structures as indicated by IR spectroscopy. Furthermore, the silver(i) perfluoroalcoholates can be used as easy-to-handle transfer reagents for the synthesis of Cu[OCF3], Cu[OC2F5], [PPh4][Au(CF3)3(OCF3)], and fluorinated alkyl ethers.
Weniger anzeigenTriazaphospholes are potential polydentate ligands due to the presence of both phosphorus and nitrogen donor atoms within the aromatic 5-membered heterocycle. The incorporation of an additional pyridyl-substituent opens up the possibility of a post-synthesis modification via chemoselective and also stepwise alkylation exclusively of the nitrogen atoms. This can be controlled by the choice and by the stoichiometry of the electrophile and allows the targeted synthesis of a variety of novel mono- and dicationic ligands. Reaction with Cu(I)-halides causes the formation of cuprates of the type [CuXn](n-1)-, which enables coordination of the π-acidic phosphorus donor to the negatively charged metal core, which is favored over the coordination by a strongly σ-donating nitrogen atom. The use of cationic triazaphosphole derivatives can be used as a strategy to enforce the coordination of the ligand to an electron rich metal solely via the phosphorus atom. However, there is a subtle balance between the formation of either coordination polymers or dimeric structures, as the substitution pattern on the heterocycle and the nature of the halide have a large influence on the coordination motifs formed.
Weniger anzeigenMehr als 30 Jahre nach der Wende scheint der Deutungskampf um das Ende des DDR-Rundfunks nicht beigelegt zu sein. Einerseits werden die mangelnden Einflussmöglichkeiten Ostdeutscher bei der Gestaltung des Rundfunks nach 1989 kritisiert. Andererseits wird die Eingliederung in das westdeutsche Rundfunksystem als Erfolg gefeiert, wobei die verschiedenen Identifikationsmöglichkeiten hervorgehoben werden, die die neu gegründeten Landessender von Anfang an boten. Dieser Beitrag fragt, wie Ostdeutsche den DDR-Rundfunk und seine Abwicklung heute erinnern. Gestützt auf die Strukturations- und Identitätstheorie von Anthony Giddens und auf der Basis von 37 biographischen Interviews wird ein Spektrum von Deutungen aufgezeigt, die Menschen aus Ostberlin rückblickend mit dem Medienstrukturumbruch verbinden. Die Studie zeigt, dass neben einer Gruppe von Befragten, die den späten DDR-Rundfunk kaum oder gar nicht in ihre Selbsterzählungen eingebunden haben, die Vergegenwärtigung dieser Einrichtung über unterschiedliche Biographien hinweg im Modus einer Selbstvergewisserung stattfindet. Dabei werden Zuordnungen und Abgrenzungen zur DDR-Herkunft vorgenommen. Die DDR-Rundfunkgeschichte wird mit Identität aufgeladen, was zum einen auf die medial dominanten DDR- und Ost-Diskurse zurückzuführen ist, zum anderen auf die verschiedenen (Kollektiv‑)Erfahrungen und Lebensbedingungen der Ostdeutschen nach 1989.
Weniger anzeigenAccurate ensemble forecasts of heavy precipitation in India are vital for many applications and essential for early warning of damaging flood events, especially during the monsoon season. In this study we investigate to what extent Quantile Mapping (QM) and Ensemble Model Output Statistics (EMOS) statistical postprocessing reduce errors in precipitation ensemble forecasts over India, in particular for heavy precipitation. Both methods are applied to day-1 forecasts at 12-km resolution from the 23-member National Centre for Medium Range Weather Forecasting (NCMRWF) global ensemble prediction system (NEPS-G). By construction, QM leads to distributions close to the observed ones, while EMOS optimizes the ensemble spread, and it is not a priori clear which is better suited for practical applications. The methods are therefore compared with respect to several key aspects of the forecasts: local distributions, ensemble spread, and skill for forecasting precipitation amounts and the exceedance of heavy-precipitation thresholds. The evaluation includes rank histograms, Continuous Ranked Probability Skill Scores (CRPSS), Brier Skill Scores (BSS), reliability diagrams, and receiver operating characteristic. EMOS performs best not only with respect to correcting under- or overdispersive ensembles, but also in terms of forecast skill for precipitation amounts and heavy precipitation events, with positive CRPSS and BSS in most regions (both up to about 0.4 in some areas), while QM in many regions performs worse than the raw forecast. QM performs best with respect to the overall local precipitation distributions. Which aspects of the forecasts are most relevant depends to some extent on how the forecasts are used. If the main criteria are the correction of under- or overdispersion, forecast reliability, match between the forecasted distribution for individual days and observations (CRPSS), and the skill in forecasting heavy-precipitation events (BSS), then EMOS is the better choice for postprocessing NEPS-G forecasts for short lead times.
Weniger anzeigenThe photothermal therapeutic effect on tumors located at different subcutaneous depths varies due to the attenuation of light by tissue. Here, based on the wavelength-dependent optical attenuation properties of tissues, the tumor depth is assessed using a multichannel lanthanide nanocomposite. A zeolitic imidazolate framework (ZIF-8)-coated nanocomposite is able to deliver high amounts of the hydrophilic heat shock protein 90 inhibitor epigallocatechin gallate through a hydrogen-bonding network formed by the encapsulated highly polarized polyoxometalate guest. It is superior to both bare and PEGylated ZIF-8 for drug delivery. With the assessment of tumor depth and accumulated amount of nanocomposite by fluorescence, an irradiation prescription can be customized to release sufficient HSP90 inhibitor and generate heat for sensitized photothermal treatment of tumors, which not only ensured therapeutic efficacy but also minimized damage to the surrounding tissues.
Weniger anzeigenInternet searches for health-related purposes are common, with search engines like Google being the most popular starting point. However, results on the popularity of health information-seeking behaviors are based on self-report data, often criticized for suffering from incomplete recall, overreporting, and low reliability. Therefore, the current study builds on user-centric tracking of Internet use to reveal how individuals actually behave online. We conducted a secondary analysis of passively recorded Internet use logs to examine the prevalence of health-related search engine use, the types of health information searched for, and the sources visited after the searches. The analysis revealed two key findings. 1) We largely support earlier survey-based findings on the prevalence of online health information seeking with search engines and the relatively minor differences in information-seeking behaviors between socio-demographic groups. 2) We provide a more granular picture of the process of HISB using search engines by identifying different selection patterns depending on the scope of the searches.
Weniger anzeigenThe phytosteroid ecdysterone is classified as an anabolic agent and has been included on the monitoring list of the World Anti-Doping Agency since 2020. Therefore, the consumption of food rich in ecdysterone, such as quinoa and spinach, is the focus of a lively debate. Thus, the urinary excretion of ecdysterone and its metabolites in humans was investigated following quinoa consumption alone and in combination with spinach. Eight participants (four male and four female) were included, and they ingested 368 ± 61 g cooked quinoa alone and in combination with 809 ± 115 g spinach after a washout. Post-administration urines were analyzed by LC-MS/MS. After intake of both preparations, ecdysterone and two metabolites were excreted in the urine. The maximum concentration of ecdysterone ranged from 0.44 to 5.5 µg/mL after quinoa and from 0.34 to 4.1 µg/mL after quinoa with spinach. The total urinary excreted amount as parent drug plus metabolites was 2.61 ± 1.1% following quinoa intake and 1.7 ± 0.9% in combination with spinach. Significant differences were found in the total urinary excreted amount of ecdysterone, 14-deoxy-ecdysterone, and 14-deoxy-poststerone. Only small portions of ecdysterone from quinoa and the combination with spinach were excreted in the urine, suggesting that both quinoa and spinach are poor sources of ecdysterone in terms of bioavailability.
Weniger anzeigenEarly human habitation of the arid to semiarid Central Iranian Plateau was strongly connected to the availability of water and associated natural hazards, such as flooding and drought events. In this geoarchaeological study, we focus on the occupation at the prehistoric site of Ajor Pazi within the formerly active fluvial environment of the Varamin Plain. Through radiocarbon and luminescence-dated sediment cross-sections, we apply multivariate statistics to sedimentological characteristics of bulk samples collected during a rescue excavation in 2018. Based on facies interpretations, we differentiate depositional processes and present their implications for the environs of Ajor Pazi. Our results show evidence of settlement activities between 6.4 and 5.6 ka cal B.P. (4.4–3.6 ka cal. B.C.E.). Phases of reduced geomorphodynamics can be distinguished when soil-forming processes take place. Our findings provide insights into the hitherto scarcely explored Transitional Chalcolithic II period during which the site of Ajor Pazi emerged and began to shape its environs.
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