1,721,014 research outputs found
Regeneration Potential of Floodplain Forests Under the Influence of Nonnative Tree Species: Soil Seed Bank Analysis in Northern Italy
No full textSoil seed banks are the ecological memory of plant communities and might represent their regeneration potential. This study examines the soil seed bank in hardwood floodplain forests of the biosphere reserve “Valle del Ticino” (Northern Italy) to find out whether the natural forest vegetation can potentially be restored by the soil seed bank. We compared near natural forests of the phytosociological association Polygonato multiflori–Quercetum roboris with stands dominated by the nonnative tree species Robinia pseudoacacia and Prunus serotina in order to investigate whether the composition of the soil seed bank is significantly influenced by the composition of the main canopy tree species and soil properties. Soil seed bank samples were taken from 20 randomly selected plots in stands that were differentiated into four groups related to the dominant forest canopy species. The germinated plants were counted and their species determined. A total of 2,427 plants belonging to 84 species were recorded. The composition of the dominant tree species and soil parameters significantly influence the composition of the seed bank. The similarity with the standing vegetation was very low. Only 13% of the species in the soil seed bank represent the target vegetation. The low percentage of target species and the high percentage of nonnative species imply that the regeneration of near-natural forest vegetation from the soil seed bank is not feasible. Consequently, disturbances that may activate the soil seed bank should be minimized. Thus, we recommend stopping the mechanical removal of the nonnative tree species in the Ticino Park
Haruldaste muldmetallide f\ufctokaevandamine: risosf\ue4\ue4ri protsesside ja geokeemiliste protsesside d\ufcnaamika pinnases. Phytomining of Rare Earth Elements: Dynamics of Rhizosphere Processes and Element Interactions in the Soil
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Verfahrensentwicklung zur Germaniumgewinnung aus Biomasse
Full text linkGermanium wird in der Regel als Nebenkomponente in der Zink- oder Kupfer-Metallurgie gewonnen. Ein Beitrag, auch einheimische Ressourcen (z.B. Haldenmaterialien) nutzen zu können, besteht in der Mobilisierung des bodengebundenen Germaniums über Pflanzen (Phytomining). In der Arbeit wurden drei Verfahrenskonzepte für die Germaniumgewinnung über die Akkumulation in Pflanzen entwickelt. Der fermentative Aufschluss des Pflanzenmaterials in einem Biogasprozess ist dabei ein Schlüsselschritt für die Wirtschaftlichkeit des Verfahrens. Weiterhin erwies sich als maßgeblich, daß es gelang, die Germaniumfraktion nahezu vollständig im festen Gärrest zu binden. Die anschließende energetische Verwertung des germaniumhaltigen festen Rückstandes liefert eine germaniumhaltige Asche, die nasschemisch gelaugt und extraktiv auf GeO2 aufbereitet wird. Eine Machbarkeitsstudie zeigt Möglichkeiten und Grenzen hinsichtlich Kosten und Rentabilität der Germaniumgewinnung über Phytomining.:Inhaltsverzeichnis
Inhaltsverzeichnis ................................................................................................... 1
Symbol- und Abkürzungsverzeichnis ...................................................................... 3
1 Einleitung ..................................................................................................... 5
2 Allgemeiner Teil ........................................................................................... 9
2.1 Biomasse als alternative Germaniumquelle ................................................... 9
2.2 Analytik von Germanium ............................................................................. 19
2.2.1 Anpassung der Flüssigkeitsanalytik für die GF-AAS .................................... 23
2.2.2 Anpassung der Feststoffanalytik für die GF-AAS ......................................... 31
2.2.3 Germaniumgehalte von weiteren Naturstoffen ............................................. 40
2.3 Biomasseaufschluss .................................................................................... 48
2.3.1 Charakterisierung von Biomassen zur stofflichen Verwertung ..................... 48
2.3.2 Aufschluss mit Mineralsäuren und Basen .................................................... 53
2.3.3 Fermentativer Aufschluss ............................................................................ 63
2.3.4 Einfluss von Separationstechniken für Gärreste auf die
Germaniumverteilung .................................................................................. 78
2.3.5 Thermischer Aufschluss von Biomassen ..................................................... 84
2.4 Anreicherung von Germanium ..................................................................... 88
2.4.1 Flüssig/Flüssig-Extraktion ............................................................................ 88
2.4.1.1 pH-Wert-Abhängigkeit ............................................................................... 91
2.4.1.2 Einfluss der Extraktionsmittelkonzentration .............................................. 93
2.4.1.3 Einfluss des Komplexierungsreagenz‘s .................................................... 94
2.4.1.4 Einfluss der Volumenverhältnisse der Extraktionsphasen ........................ 95
2.4.1.5 Optimierung der Kontaktzeit ...................................................................... 96
2.4.1.6 Einfluss verschiedener Komplexliganden ................................................. 97
2.4.1.7 Extraktion aus Laugungslösungen definierter Germaniumkonzentration .100
2.4.1.8 Anwendung auf reale Prozesslösungen .................................................. 104
2.4.2 Destillation über Germanium(IV)-chlorid .................................................... 105
2.5 Verfahrenskonzepte zur Germaniumgewinnung aus Biomassen ............... 114
2.5.1 Germaniumgewinnung nach Biomasselaugung ......................................... 115
2.5.2 Germaniumgewinnung nach thermischem Aufschluss............................... 117
2.5.3 Germaniumgewinnung nach Fermentation von Biomassen ....................... 119
2.6 Wirtschaftlichkeitsbetrachtung zur Germaniumgewinnung aus Biomassen 121
3 Zusammenfassung und Ausblick ........................................................... 130
4 Experimenteller Teil ................................................................................ 133
4.1 Verwendete Chemikalien ........................................................................... 133
4.2 Verwendete Geräte ................................................................................... 134
4.3 Analytik der Graphitrohrofen - Atomabsorptionsspektrometrie ................... 134
4.4 Analytik der Massenspektrometrie mit induktiv gekoppeltem Plasma ........ 135
4.5 Charakterisierung von Biomassen ............................................................. 135
4.5.1 Trockensubstanz ....................................................................................... 135
4.5.2 Extraktgehalt ............................................................................................. 136
4.5.3 Cellulosegehalt .......................................................................................... 136
4.5.4 Holocellulosegehalt ................................................................................... 136
4.5.5 Ligningehalt ............................................................................................... 136
4.5.6 Organische Trockensubstanz .................................................................... 137
4.6 Aufschluss mit Säuren und Basen ............................................................. 137
4.6.1 Laugung von Biomassen ........................................................................... 137
4.6.2 Bestimmung TOC und IR .......................................................................... 137
4.6.3 Verzuckerung von Biomassen ................................................................... 137
4.7 Fermentativer Aufschluss .......................................................................... 138
4.8 Absorption von Germanium an Biomassen ................................................ 139
4.9 Physikalische Gärrestseparationen ........................................................... 139
4.9.1 Zentrifugation von Gärresten ..................................................................... 139
4.9.2 Druckfiltration von Gärresten ..................................................................... 140
4.9.3 Sedimentation von Gärresten mit Zusätzen ............................................... 140
4.10 Thermogravimetrische Analyse ................................................................. 140
4.11 Thermischer Aufschluss ............................................................................ 141
4.12 Wasserlaugung von Aschen ...................................................................... 141
4.13 Flüssig/Flüssig-Extraktion .......................................................................... 141
4.14 Destillation über Germanium(IV)-chlorid .................................................... 142
5 Literaturverzeichnis ................................................................................ 143
6 Anhang ..................................................................................................... 15
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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