Himalayan treeline soil and foliar C:N:P stoichiometry indicate nutrient shortage with elevation

Only a few studies have addressed the soil and foliar carbon:nitrogen:phosphorus (C:N:P) stoichiometry in alpine treeline ecotones. Moreover, information on the soil nutrient availability (primarily N, P) in such ecosystems is rare. To fill these gaps, we performed a multiple data sampling in a near-natural alpine treeline ecotone in Rolwaling Himal, Nepal. Our results show strongly varying soil C:N:P ratios and nutrient availabilitywith soil depth. Caused by high monsoon precipitation and coarse-grained soils with low water-holding capacities, a vertical transport of nutrients and potentially mineralizable soil organic matter (SOM) in soils occurs, which is a general problem in the study area impeding growing conditions for trees. Soil N and P availability, and soil C:P and N:P ratios decrease significantly as elevation increases, especially at the transition from krummholz (dominated by rhododendron campanulatum) to the alpine tundra (dwarf scrub heath). Soil C:N ratios increase significantly with elevation, most notably from the subalpine forest to krummholz and the alpine tundra. These altitudinal trends indicate increasing nutrient (N, P) shortage especially in the alpine tundra. LowNand P availability in alpine tundra soils are likely caused by a lower litter input from dwarf shrub vegetation, and a decline in litter mineralization in this altitudinal zone resulting in small accumulation of SOM. Nutrient availability in the entire study area is generally limited by low soil pH (from 2.5 to 4). In total six investigated tree species show diverse relationships between foliar and soil stoichiometric ratios, and soil nutrient availability. Significantly increasing foliar C:N and C:P ratios with elevation due to significantly decreasing foliar N and P concentrations suggest a limitation in N and P. Foliar N:P ratios indicate N rather than P limitation. Contrary to previous studies from different alpine treeline ecotones, we do not consider the Rolwaling treeline ecotone as an area of nutrient accumulation. We conclude that altitudinal variations in stand structures themselves govern nutrient cycling through the input of C, N, and P into soils by differences in leaf fall

Phosphordünger aus Klärschlamm: Evaluierung von Pyrolysekohle und Alkalipyrolyse

Phosphorus (P) in sewage sludge holds the main proportion of P currently lost in waste streams, and options to recycle it for agriculture are needed. Pyrolysis is a promising local alternative to centralized sewage sludge incineration. Pathogens and organic pollutants are destroyed and a carbon-rich substrate known as biochar is formed. We evaluated pyrolysis of sewage sludge as well as sintering of pyrolysis char with alkali salts. The products were applied in a pot experiment with calcareous and acidic soils to determine P uptake by ryegrass (Lolium multiflorum) and changes in soil pH, available P and cation exchange capacity. Two products were also tested in a field experiment with maize (Zea mays) on a neutral soil. Cadmium and mercury were partly lost during pyrolysis. The pot experiment revealed interactions between soil pH and P use efficiency of the various products, including reference fertilizers permitted in organic farming. Pyrolysis changed plant P availability only slightly compared to the parent sewage sludge, but sintering with alkali salts increased plant P availability to levels comparable to triple superphosphate. Potential implications for organic agriculture are discussed

Carbon cycling and translocation processes in Baltic Sea coastal dune topsoils

Chronosequenzen bieten ideale Voraussetzungen zur Analyse des Einflusses pedo­genetischer Prozesse auf die Kohlenstoff- und Stickstoffdynamik im Boden. Die sich ändernden Verfügbarkeiten von Kohlenstoff (C) und Stickstoff (N) während der Pedogenese beeinflussen den Umsatz von organischer Bodensubstanz (OBS). Vergangene Arbeiten konnten zeigen, dass die Verteilung stabiler C Isotope im Oberboden zur Abschätzung des Umsatzes von OBS herangezogen werden kann. Entlang einer Dünenchronosequenz in Haast (Neuseeland) stieg der Umsatz von OBS zu Beginn der Pedogenese und erreichte einen Tiefpunkt nach dem Zerfall der Bäume aus erster Generation. Zudem zeigten C-13 Tiefenprofile Parallelen zur vertikalen Verteilung stabiler N Isotope im Oberboden. Ziele dieser Studie sind die Untersuchung von C-13 und 15-N Tiefenprofilen entlang einer Dünenchronosequenz der Ostsee. Hierzu werden entlang einer 60 bis 5500 Jahre alten Dünensequenz bei Swinemünde (Polen) Bodenproben entnommen und anhand ihrer C und N Isotopenverteilungen analysiert. Es wird ein Anstieg des Umsatzes durch ansteigende C Gehalte in frühen Phasen der Pedogenese erwartet. Atmosphärische N Deposition kann einen erheblichen Effekt auf die Vegetations- und mikrobielle Zusammensetzung sowie Umsatzprozesse während der Boden- und Ökosystementwicklung haben. Große Unterschiede der N Depositionen zwischen Dünengebieten der südlichen Ostsee und Neuseeland könnten daher 13-C sowie 15-N Tiefenprofile beeinflussen. Die gewonnen Daten liefern einen wichtigen Beitrag zum Verständnis der C Sequestrierung und der Stickstoffdynamik während der Pedogenese

XUV frequency comb production with an astigmatism-compensated enhancement cavity

We have developed an extreme ultraviolet (XUV) frequency comb for performing ultra-high precision spectroscopy on the many XUV transitions found in highly charged ions (HCI). Femtosecond pulses from a 100 MHz phase-stabilized near-infrared frequency comb are amplified and then fed into a femtosecond enhancement cavity (fsEC) inside an ultra-high vacuum chamber. The low-dispersion fsEC coherently superposes several hundred incident pulses and, with a single cylindrical optical element, fully compensates astigmatism at the w0 = 15 µm waist cavity focus. With a gas jet installed there, intensities reaching ∼ 1014 W/cm2 generate coherent high harmonics with a comb spectrum at 100 MHz rate. We couple out of the fsEC harmonics from the 7th up to the 35th (42 eV; 30 nm) to be used in upcoming experiments on HCI frequency metrology

Successful treatment of a recurrent granulation polyp in the airways with high-dose-rate brachytherapy: a case report

Background Benign central airway tumors are very rare diseases. Their unspecific symptoms are responsible for late diagnosis. Endoscopic interventions with different techniques and tools are widely used for their treatment. However, in certain cases interventional endoscopy might be unsuccessful and therefore other methods such as high-dose-rate brachytherapy could be a therapeutic option. Case presentation A 76-year-old white German woman was referred to our clinic for an endoscopic treatment of a recurrent granulation polyp in her left main bronchus. She had dyspnea, coughing, and mucus retention. Three times resections via bronchoscopy were performed within less than a year. After each intervention the polyp regrew inside her left main bronchus causing a repeat of the initial symptoms. She presented to our clinic less than 1 month since the last intervention. Twice we performed a rigid bronchoscopy in total anesthesia where we resected the granulation polyp with a snare wire loop and did an argon plasma coagulation of its base. Due to the recurrent growing of the granuloma, we performed a high-dose-rate brachytherapy in conscious sedation after another interventional bronchoscopy with a resection of the polyp and argon plasma coagulation of the base. Three months after brachytherapy our patient came to our clinic for a follow-up with none of the initial symptoms. Only a small remnant of the polyp without a significant occlusion of her bronchus was visualized by bronchoscopy. Furthermore, 6 months after brachytherapy she was not presenting any of the initial symptoms. Conclusions This case report shows that high-dose-rate brachytherapy is a therapeutic option for the treatment of benign airway stenosis when other interventional treatments are not or are less than successful. However, further investigations are needed to prove the effectiveness and reliability of the method

Synthesis of Passerini-3CR Polymers and Assembly into Cytocompatible Polymersomes

© 2020 The Authors. Published by Wiley-VCH GmbH The versatility of the Passerini three component reaction (Passerini-3CR) is herein exploited for the synthesis of an amphiphilic diblock copolymer, which self-assembles into polymersomes. Carboxy-functionalized poly(ethylene glycol) methyl ether is reacted with AB-type bifunctional monomers and tert-butyl isocyanide in a single process via Passerini-3CR. The resultant diblock copolymer (P1) is obtained in good yield and molar mass dispersity and is well tolerated in model cell lines. The Passerini-3CR versatility and reproducibility are shown by the synthesis of P2, P3, and P4 copolymers. The ability of the Passerini P1 polymersomes to incorporate hydrophilic molecules is verified by loading doxorubicin hydrochloride in P1DOX polymersomes. The flexibility of the synthesis is further demonstrated by simple post-functionalization with a dye, Cyanine-5 (Cy5). The obtained P1-Cy5 polymersomes rapidly internalize in 2D cell monolayers and penetrate deep into 3D spheroids of MDA-MB-231 triple-negative breast cancer cells. P1-Cy5 polymersomes injected systemically in healthy mice are well tolerated and no visible adverse effects are seen under the conditions tested. These data demonstrate that new, biodegradable, biocompatible polymersomes having properties suitable for future use in drug delivery can be easily synthesized by the Passerini-3CR

The Evolution of Ecological Diversity in Acidobacteria

Acidobacteria occur in a large variety of ecosystems worldwide and are particularly abundant and highly diverse in soils. In spite of their diversity, only few species have been characterized to date which makes Acidobacteria one of the most poorly understood phyla among the domain Bacteria. We used a culture-independent niche modeling approach to elucidate ecological adaptations and their evolution for 4,154 operational taxonomic units (OTUs) of Acidobacteria across 150 different, comprehensively characterized grassland soils in Germany. Using the relative abundances of their 16S rRNA gene transcripts, the responses of active OTUs along gradients of 41 environmental variables were modeled using hierarchical logistic regression (HOF), which allowed to determine values for optimum activity for each variable (niche optima). By linking 16S rRNA transcripts to the phylogeny of full 16S rRNA gene sequences, we could trace the evolution of the different ecological adaptations during the diversification of Acidobacteria. This approach revealed a pronounced ecological diversification even among acidobacterial sister clades. Although the evolution of habitat adaptation was mainly cladogenic, it was disrupted by recurrent events of convergent evolution that resulted in frequent habitat switching within individual clades. Our findings indicate that the high diversity of soil acidobacterial communities is largely sustained by differential habitat adaptation even at the level of closely related species. A comparison of niche optima of individual OTUs with the phenotypic properties of their cultivated representatives showed that our niche modeling approach (1) correctly predicts those physiological properties that have been determined for cultivated species of Acidobacteria but (2) also provides ample information on ecological adaptations that cannot be inferred from standard taxonomic descriptions of bacterial isolates. These novel information on specific adaptations of not-yet-cultivated Acidobacteria can therefore guide future cultivation trials and likely will increase their cultivation success