Manganese speciation in soil studied by Mn K-edge X-ray absorption spectroscopy

Manganese (Mn) is one of the most redox-sensitive elements on Earth, participating in a plethora of environmental processes. Its reactivity and mobility largely rely on its specific chemical form, i.e., Mn2+, Mn3+, or Mn4+. In soils, Mn is recognized as a major player controlling oxidative transformation of organic and inorganic constituents. Various Mn minerals are found in soils, but among all, Mn oxides and hydroxides are commonly referred to as key species, whose precipitation and dissolution primarily control the sequestration of (heavy) metal pollutants and nutrients. Despite their ecological relevance, their typically low concentration and poor crystallinity in soils render their analytical accessibility challenging. Thus, studies identifying and quantifying effectively occurring chemical forms of Mn in soils are remarkably rare. To overcome this lack of knowledge, this work provides the first Mn K-edge (6,539 eV) X-ray absorption spectroscopy (XAS) library of soil Mn species and presents the first quantitative species inventory of bulk soils. The first study compiles a database of 32 well characterized (in)organic Mn compounds potentially occurring in soils. Their Mn average oxidation state (AOS) was inferred from Mn K-edge X-ray absorption near edge structure (XANES) and their local (<5 Å) Mn coordination environment form extended X-ray absorption fine structure (EXAFS) spectroscopy. Principal component and cluster analyses of k2-weighted EXAFS spectra of Mn compounds implied that at least five primary Mn species groups can be identified and quantified by EXAFS linear combination fit analysis of environmental samples. The results highlight the potential of Mn K-edge EXAFS spectroscopy to assess bulk Mn speciation in soils and establish the first extensive framework for the analysis and interpretation of Mn XAS spectra of natural samples. The second study explores Mn speciation of 47 soil samples (45.1-2,280 mg/kg Mn) of nine Central European soils by XAS and relates the obtained information to major soil properties. In litter horizons, Mn was mainly present in the form of organically complexed and ‘physisorbed’ Mn, but also minor amounts of manganates, Mn(III) oxyhydroxides, and silicate-bound Mn occurred. In all mineral soil horizons, manganates clearly dominated, but we also highlight the occurrence of feitknechtite (β-MnOOH), groutite (α-MnOOH), and hausmannite (Mn3O4) in acidic soils. The low occurrence of primary silicate-bound and exchangeable Mn phases confirms the early release of Mn from primary silicate minerals and the rapid conversion into manganates, respectively. These results have far-reaching implications for the functioning of soil and biogeochemical element cycles, as manganates play a fundamental role in metal binding, plant nutrition, and redox-related processes in the critical zone

Telehealth and Home Health Occupational Therapy: Clients’ Perceived Satisfaction With and Perception of Occupational Performance

Home health care agencies are restructuring service delivery models to address quality of care and client satisfaction while containing costs. New regulatory changes and the public health emergency as a result of the COVID-19 pandemic brought immediate need for alternative care models. Telehealth has been recognized as a feasible means to provide health care. This quasi-experimental pretest-posttest study examined the feasibility of performing occupational therapy telehealth visits as adjunct to on-site visits for homebound clients (N=9). The OASIS data collection set, Canadian Occupational Performance Measure, and a survey were used to collect data. This combination of visits resulted in clinically and statistically significant improvements in client perception of performance and satisfaction. Findings showed that participants felt this visit model met their needs and they would recommend to others. Results of this study warrant a larger study involving physical therapy and speech language pathology disciplines. 

Classification of small links in the unmarked solid torus

We introduce a framework to analyze knots and links in an unmarked solid torus. We discuss invariants that detect when such links are equivalent under an ambient homeomorphism, and show that the multivariable Alexander polynomial is such in invariant. We compute, for links with low wrapping number, bounds on the degree of a Dehn twist needed to transform one into the other that depend on the dichromatic Kauffman polynomial. Finally, we use this to give a classification of all non-split links up to 6 crossings in the unmarked solid torus.Comment: 62 pages, many figure

Non-Esterified Plant Oils as Fuel-Engine Characteristics, Emissions and Mutagenic Effects of Particulate Matter

Pflanzenöle können einen gewissen Beitrag für eine erneuerbare, nahezu CO2-neutrale Kraftstoffversorgung leisten. Die nicht-veresterten Pflanzenöle haben im Gegensatz zu veresterten Ölen eine günstige Energie- und CO2-Bilanz. Deshalb werden hier die naturbelassenen, aber raffinierten Pflanzenöle auf ihre Eignung als Kraftstoff in Dieselmotoren und deren Emissionen detailliert untersucht. Versuche wurden mit drei verschiedenen Dieselmotoren durchgeführt.Plant oils may be used as a sustainable, nearly CO2 neutral fuel for diesel engines. This work investigates experimentally the particulate and gaseous emissions of diesel engines fuelled with non-esterified, pure plant oils with the quality standard of DIN V 51605 (Weihenstephan RK-Qualitätsstandard 05/2000). The data are collected from three engines: – Common rail passenger car engine from Opel AG – Truck engine from VOLVO – Truck engine from MAN A

Diesel-elektrischer Hybridantrieb für kommunale Arbeitsmaschinen

Angepasste Hybridantriebe in mobilen Arbeitsmaschinen (off-highway Anwendungen) versprechen wegen der typischerweise auftretenden Lastzyklen mit ausgeprägten, häufigen und schnellen Laständerungen folgende Vorteile: geringerer Kraftstoffverbrauch, Einsatz eines Dieselmotors kleinerer Leistung, dadurch Erfüllung strikter werdender Emissionsvorschriften (TIER 4, EURO 5) ohne oder mit reduzierter Abgasnachbehandlung, Lärmreduktion, weitere Einsparpotenziale durch Elektrifizierung der Fahrzeugfunktionen möglich (Erhöhung des Hybridisierungsgrads), höhere Produktivität durch höhere Antriebsdynamik.Several duty cycles have been performed with the LADOG multipurpose community vehicle equipped with a conventional diesel engine drive train. Based on these results, simulation calculations have been performed to estimate the fuel savings which can be achieved if this mobile machine would be equipped with a parallel diesel-electric hybrid drive train. Two hybrid configurations were considered, one with the original diesel engine and one with a right-sized, i.e. a smaller diesel engine. Several operation modes of the hybrid were simulated like start-stop function, recuperation, boosting and diesel engine operation for optimized fuel consumption (characteristic mapping). The simulation results showed fuel savings up to 20 % even for this community vehicle which seemed not to be attractive for hybridization. This LADOG vehicle is actually modified by the hybrid drive train substituting the pure diesel drive train. The experimental proof of the simulations is under way

Konventionelle Dampfkraftwerke

Das Dampfkraftwerk beruht als thermisches Kraftwerk auf einem thermodynamischen Kreisprozess, der Wärme in technische Arbeit umwandelt. Die Arbeit wird mittels Elektrogenerator als elektrische Energie abgegeben

Energetische Müllverwertung

In den 1970er-Jahren entstand in der Bundesrepublik Deutschland das Bewusstsein für die Problematik von Mülldeponien mit ihren Sickerwässern und entweichenden Gasen. Die lokalen Müllkippen wurden zugunsten weniger zentraler, überwachter Anlagen geschlossen (Faustregel: Eine Zentraldeponie pro Landkreis)

Überblick, Energiequellen und Energiebedarf

Unter fossilen Energieträgern verstehen sich energie- und kohlenstoffhaltige Stoffe, die in mehreren Millionen Jahren aus Biomassen unter dafür günstigen Bedingungen (Sauerstoffausschluss) gebildet wurden. Das geologische Alter von Steinkohle beträgt über 250 Millionen Jahre, das von Braunkohle ca. 50 Millionen. Derzeit werden deutlich mehr fossile Energieträger verbraucht als nachgebildet. Während in Deutschland die Stilllegung von Dampfkraftwerken, die mit Steinkohle befeuert werden, begonnen hat, steigt global der Verbrauch dieser Brennstoffe weiterhin an. Die Steinkohleförderung erreichte im Jahr 2019 weltweit den Wert von 7,3 Milliarden Tonnen, mit einer Steigerung von immerhin fast 3 % gegenüber dem Vorjahr 2018 nach [1]. Dieser Anstieg erfolgte hauptsächlich in China und Indonesien – in Deutschland ging der Kohleverbrauch in diesem Zeitraum zurück