Investigation of Cu poor and Cu rich Cu In,Ga Se2 CdS interfaces using hard X ray photoelectron spectroscopy

Cu poor and Cu rich Cu In,Ga Se2 CIGSe absorbers were used as substrates for the chemical bath deposition of ultrathin CdS buffer layers in the thickness range of a few nanometers in order to make the CIGSe CdS interface accessible by hard X ray photo emission spectroscopy. The composition of both, the absorber and the buffer layer as well as the energetics of the interface was investigated at room temperature and after heating the samples to elevated temperatures 200 C, 300 C and 400 C . It was found that the amount of Cd after the heating treatment depends on the near surface composition of the CIGSe absorber. No Cd was detected on the Cu poor surface after the 400 C treatment due to its diffusion into the CIGSe layer. In contrast, Cd was still present on the Cu rich surface after the same treatment at 400

Räumliche Heterogenität der Phosphor-Konzentration und P-Speziierung in Waldböden in Abhängigkeit vom Wurzelsystem

Einzelne Bäume unterscheiden sich sowohl hinsichtlich ihres Phosphor(-P)-inputs in den Boden als auch ihrer P-Aufnahmeraten aus dem Boden. Es ist daher sehr wahrscheinlich, dass diese zur Entstehung von P-Heterogenitätsmustern im Boden beitragen. Andererseits können bestehende P-Verteilungsmuster die P-Versorgungsstrategien von Bäumen und assoziierten Mikroorganismen beeinflussen. Diese Studie untersucht den Zusammenhang zwischen räumlicher Heterogenität der P-Konzentration und P-Speziierung zweier Standorte mit unterschiedlichem P-Versorgungszustand sowie dem Wurzelsystem einzelner Buchen auf unterschiedlichen Skalen (Aggregat bis Profilskala). Darüber hinaus wird der Einfluss unterschiedlicher P-Verteilungen auf die P-Aufnahme von Buchen und Mikroorganismen analysiert. Die räumliche Heterogenität der Boden-P-Vorräte und bodenbiologischer Parameter wurde mittels NanoSIMS, μ-XRF, μ-XANES, Enzymanalyse und Suberinanalyse sowie geostatistischer Auswerteverfahren erfasst. Desweiteren wurde die Aufnahme von 33P-Eisen(III) phosphat bei verschiedenen räumlichen Heterogenitätsmustern in Buchen und Mikroorganismen in Rhizotronen studiert. Die Vorräte an leicht verfügbaren P-Formen (Pi-NaHCO3) nahmen mit zunehmendem Abstand vom Wurzelsystem einzelner Buchen zu. Gleichzeitig nahm die Aktivität der alkalischen Phosphatase in Wurzelnähe ab, während die Aktivität der sauren Phosphatase anstieg. Am P-reichen Standort hing die räumliche Verteilung der Ptot- und Porg-Vorräte auf der Pedon Skala vor allem von der Verteilung der organischen Bodensubstanz (OBS) aus Wurzeleinträgen (gemessen als Suberin-Konzentration) ab. Im Gegensatz dazu, konnte am P-armen Standort keine räumliche Korrelation zwischen Wurzeln und Ptot oder Porg Vorräten nachgewiesen werden. Die Bodenaggregate beider Standorte unterschieden sich hinsichtlich ihrer P-Verteilungsmuster: Der P des P-reichen Standortes war feinverteilter in Al- und Fe-Mikroaggregaten, während der P des P-armen Standortes in Überzügen von Quarzkörnern konzentriert war. Das Rhizotronexperiment zeigte, dass eine heterogene P-Verteilung die mikrobielle Mobilisierung und Aufnahme von P signifikant begünstigt – ein Prozess, der vorwiegend auf Pilze zurückzuführen ist. Zusammenfassend zeigen die Ergebnisse der Studie, dass Baumwurzeln und assoziierte Mikroorganismengesellschaften bestehende P Heterogenitätsmuster zur Nährstoffakquise nutzen, aber ebenso zur Entstehung neuer Verteilungsmuster beitragen

Glow discharge optical emission spectrometry for quantitative depth profiling of CIGS thin films

Determining elemental distributions dependent on the thickness of a sample is of utmost importance for process optimization in different fields e.g. from quality control in the steel industry to controlling doping profiles in semiconductor labs. Glow discharge optical emission spectrometry GD OES is a widely used tool for fast measurements of depth profiles. In order to be able to draw profound conclusions from GD OES profiles, one has to optimize the measurement conditions for the given application as well as to ensure the suitability of the used emission lines. Furthermore a quantification algorithm has to be implemented to convert the measured properties intensity of the emission lines versus sputtering time to more useful parameters, e.g. the molar fractions versus sample depth depth profiles . In this contribution a typical optimization procedure of the sputtering parameters is adapted to the case of polycrystalline Cu In,Ga S,Se 2 thin films, which are used as absorber layers in solar cell devices, for the first time. All emission lines used are shown to be suitable for the quantification of the depth profiles and a quantification routine based on the assumption of constant emission yield is used. The accuracy of this quantification method is demonstrated on the basis of several examples. The bandgap energy profile of the compound semiconductor, as determined by the elemental distributions, is compared to optical measurements. The depth profiles of Na the main dopant in these compounds are correlated with measurements of the open circuit voltage of the corresponding devices, and the quantification of the sample depth is validated by comparison with profilometry and X ray fluorescence measurement

Decadal soil carbon accumulation across Tibetan permafrost regions

Acknowledgements We thank the members of Peking University Sampling Teams (2001–2004) and IBCAS Sampling Teams (2013–2014) for assistance in field data collection. We also thank the Forestry Bureau of Qinghai Province and the Forestry Bureau of Tibet Autonomous Region for their permission and assistance during the sampling process. This study was financially supported by the National Natural Science Foundation of China (31670482 and 31322011), National Basic Research Program of China on Global Change (2014CB954001 and 2015CB954201), Chinese Academy of Sciences-Peking University Pioneer Cooperation Team, and the Thousand Young Talents Program.Peer reviewedPostprintPostprin

Assimilation of alternative sulfur sources in fungi

Fungi are well known for their metabolic versatility, whether it is the degradation of complex organic substrates or the biosynthesis of intricate secondary metabolites. The vast majority of studies concerning fungal metabolic pathways for sulfur assimilation have focused on conventional sources of sulfur such as inorganic sulfur ions and sulfur-containing biomolecules. Less is known about the metabolic pathways involved in the assimilation of so-called “alternative” sulfur sources such as sulfides, sulfoxides, sulfones, sulfonates, sulfate esters and sulfamates. This review summarizes our current knowledge regarding the structural diversity of sulfur compounds assimilated by fungi as well as the biochemistry and genetics of metabolic pathways involved in this process. Shared sequence homology between bacterial and fungal sulfur assimilation genes have lead to the identification of several candidate genes in fungi while other enzyme activities and pathways so far appear to be specific to the fungal kingdom. Increased knowledge of how fungi catabolize this group of compounds will ultimately contribute to a more complete understanding of sulfur cycling in nature as well as the environmental fate of sulfur-containing xenobiotics

Global data on earthworm abundance, biomass, diversity and corresponding environmental properties

Publisher Copyright: © 2021, The Author(s).Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provided directly by authors, were collated with information on site locations, including coordinates, habitat cover, and soil properties. Datasets were required, at a minimum, to include abundance or biomass of earthworms at a site. Where possible, site-level species lists were included, as well as the abundance and biomass of individual species and ecological groups. This global dataset contains 10,840 sites, with 184 species, from 60 countries and all continents except Antarctica. The data were obtained from 182 published articles, published between 1973 and 2017, and 17 unpublished datasets. Amalgamating data into a single global database will assist researchers in investigating and answering a wide variety of pressing questions, for example, jointly assessing aboveground and belowground biodiversity distributions and drivers of biodiversity change.Peer reviewe

Global data on earthworm abundance, biomass, diversity and corresponding environmental properties

Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provided directly by authors, were collated with information on site locations, including coordinates, habitat cover, and soil properties. Datasets were required, at a minimum, to include abundance or biomass of earthworms at a site. Where possible, site-level species lists were included, as well as the abundance and biomass of individual species and ecological groups. This global dataset contains 10,840 sites, with 184 species, from 60 countries and all continents except Antarctica. The data were obtained from 182 published articles, published between 1973 and 2017, and 17 unpublished datasets. Amalgamating data into a single global database will assist researchers in investigating and answering a wide variety of pressing questions, for example, jointly assessing aboveground and belowground biodiversity distributions and drivers of biodiversity change