III. Tektonik Die saxonische Tektonik im Bilde Europas

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Behaviour of Instrumented Hollow Auger Pile Groups in Sandy Soil

Geotechnical and Geological Engineering - Hollow auger piles are a new solution technique being used more often in recent years as a foundation for buildings of 15 floors or less in the coastal...     

The great 1983 floods in South American large rivers: a continental hydrological modelling approach

ABSTRACT

This study provides a spatio-temporal analysis of the great floods that occurred in South America in 1983 using hydrometeorological data and outputs from a continental-scale hydrological-hydrodynamic model. In the extreme year 1983, there were three main flooding periods (February, June and July) in many South American river basins, such as the Araguaia, Tocantins, São Francisco, Uruguay, La Plata and its tributaries, resulting in high discharge of the Paraguay River for many months. Depth–area–duration curves show that 3-day precipitation events in northern regions of South America were among the largest 15 events in the period 1980–2015 but only for specific locations, whereas in southern areas, the most extreme events in the same period were for larger durations (≥7-day precipitation). Modelled total export of water volume to the oceans indicates that rivers draining to the South Atlantic reached an anomaly of 3.7 during 1983, followed by 1998 (1.9) and 1992 (1.1), all of them corresponding to El Niño years.     

Activity-composition relationship in Tschermak's substituted Fe biotites at 700°C, 2 kbar

The reaction-displacement technique was applied to the end-member reaction annite = sanidine + magnetite + H₂ in order to determine the activity of the annite component (a _Ann) in iron biotites with variable degrees of the Tschermak's substitution (^[6]Fe + ^[4]Si = ^[6]Al + ^[4]Al). Based on the simplified relation a _Ann = f _{H 2}/foH₂ (foH₂ = hydrogen fugacity of the end-member reaction at P, T), two types of experiments were performed at 700°C / 2 kbar: Type I used Fe-Al biotites of known starting composition together with sanidine + magnetite + H₂O. This assemblage was exposed to various f _{H 2} conditions (f _{H 2} < foH₂) produced in the pressure vessel either by using different ratios of water/oil as pressure medium (f _{H 2} in this case was measured by the hydrogen sensor technique), or by the Ni′NiO buffer. The composition of the Fe-Al biotites changed through incorporation or release of the annite component in response to the externally imposed f _{H 2}. By using opposite biotite starting compositions, the equilibrium composition as a function of f _H2 was bracketed. For type II, f _{H 2} in equilibrium with a specific combination of fine-grained Fe-Al biotite (+ sanidine + magnetite + H₂O) was measured internally by application of the hydrogen sensor technique. Both type I and type II experiments yield consistent results demonstrating that a fine-grained assemblage of Fe-Al biotite (+ sanidine + magnetite + H₂O) is able to act as a sliding-scale buffer. The final chemical composition of the Fe-Al biotite after the experiments was determined by electron microprobe and Mössbauer spectroscopy. The ^[4]Al and ^[6]Al in the biotites are coupled according to the Tschermak's substitution. In the tetrahedral sheet 0.1 Al-atoms per formula unit are present in excess to the amount required to balance ^[6]Al, and all Fe-Al biotites contain 8–10% Fe³⁺. Therefore, they are not members of the pure annite - siderophyllite join, but have an almost constant amount (15 Mol%) of two additional Fe³⁺-bearing components (ferri-siderophyllite and a vacancy end-member). The volume - composition relationship obtained does not indicate excess molar volumes of mixing for the annite (Ann) - siderophyllite (Sid) binary. The data are consistent with a molar volume of annite of 15.46 ± 0.02 Jbar^–1 and of 15.06 ± 0.02 Jbar^–1 for siderophyllite. The experimentally determined activity - composition relation shows that biotites on the join annite - siderophyllite deviate negatively from ideality. A symmetric interaction parameter W_AnnSid is sufficient to represent the data within error. This was constrained as: W _AnnSid = –29 ± 4 kJmol^–1. This is in contradiction to empirical interaction parameters derived from natural assemblages for this binary that predict positive deviation from ideality. Reasons for this discrepancy are discussed.     

Bankfull discharge in mountain streams: theory and practice

The results are presented of an investigation of bankfull discharge in two Polish Carpathian streams: Skawica and Krzyworzeka. Existing definitions of river bankfull were reviewed and applied in tests carried out on selected cross‐sections of the streams. The Woodyer method was given special attention, with a correspondingly detailed survey of plants characterizing river benches. Riley's bench index method and the methods of Williams, Wolman, Schumm and Brown, and Woloszyn were tested. The report concludes that bankfull discharge value for a mountain stream should not be reported as a single number, but rather as a range of discharges within which one could expect the bankfull value to lie. Copyright © 2002 John Wiley & Sons, Ltd.     

The effect of salinity on Fucus ceranoides (Ochrophyta,Phaeophyceae) in the Mondego River (Portugal)

Algae(and their extracts) are increasingly important for pharmaceutical applications due to the diversity of useful compounds they contain. The genus Fucus contains one of the most studied species,Fucus vesiculosus. The species F. ceranoides differs from the others of the genus by presenting longitudinal air-vesicles and a capacity to survive at low salinities. It is an alga that inhabits the Mondego River estuary(Portugal), at the southern limit of its distribution, and can serve as a role model to understand the effect of a salt gradient on the production of bioactive compounds. We assessed the phenolic content and antioxidant activity of different F. ceranoides extracts(e.g. methanolic, aqueous and polysaccharide) prepared from samples harvested from two different zones to evaluate if the adaptation of F. ceranoides to different salinity levels influenced its chemical composition. The antioxidant activity of the extracts was determined using 1,2-diphenyl-picrylhydrazyl(DPPH) and 2.2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS)radicals. These assays demonstrated that the methanolic extract of lyophilized F. ceranoides that grew at low salinities was the most bioactive, i.e. DPPH(IC_(50)=50.39 μg/mL) and ABTS(TEAC=2.42). The total phenolic content(Folin-Ciocalteu method) and the methanolic extract of the lyophilized F. ceranoides collected from a low salinity habitat exhibited the highest phenolic content(PGE=49.48 μg/mg of lyophilized extract)amongst those sampled. Thin layer chromatography(TLC) and Fourier transform infrared spectroscopy(FTIR) were used for the identification of compounds in the extracts. This characterization allowed confirmation that the various extracts contained almost the same compounds but with notable quantitative differences. Based on these results, we conclude that there were differences in the quantity of the compounds due to the effect of salinity. The drying methods used were also found to have influenced the quality of the extracted compounds.     

Hydric potential of the river basin: Prądnik,Polish Highlands

Human society deals with floods, drought and water pollution. Facing those problems, the question how to prevent or at least to minimalize the adverse effects of water-related issues is asked of the landscape managers. In this way, any help given to landscape managers seems to be an additional useful tool. Within this paper, an approach leading to mitigation of water-related problems is presented that relates the retention of precipitation and the use of ecosystems as a tool for improving the quality, quantity of water resources and availability throughout the region. One approach is the determination of the landscape’s hydric potential (LHP). This study examines one example of using this method within the conditions of Poland. The results of the research show that national data are entirely appropriate for implementation of the LHP method. Further, this approach revealed the classes of the hydric potential of the Pr?dnik river basin which was selected as the experimental territory. LHP results reflect the ecosystem attributes of the model river basin; areas of average LHP cover 63.26%, areas of high and limited hydric potential cover approximately 18.3% each. The spatial distribution of LHP means the results of this study provide a baseline for management of the river basin.     

High-resolution computed microtomography for the characterization of a diffusion tensor imaging phantom

This paper addresses the issue of the quantitative characterization of the structure of the calibration model (phantom) for b-matrix spatial distribution diffusion tensor imaging (BSD-DTI) scanners. The aim of this study was to verify manufacturing assumptions of the structure of materials, since phantoms are used for BSD-DTI calibration directly after manufacturing. Visualization of the phantoms’ structure was achieved through optical microscopy and high-resolution computed microtomography (µCT). Using µCT images, a numerical model of the materials structure was developed for further quantitative analysis. 3D image characterization was performed to determine crucial structural parameters of the phantom: porosity, uniformity and distribution of equivalent diameter of capillary bundles. Additionally calculations of hypothetical flow streamlines were also performed based on the numerical model that was developed. The results obtained in this study can be used in the calibration of DTI-BST measurements. However, it was found that the structure of the phantom exhibits flaws and discrepancies from the assumed geometry which might affect BSD-DTI calibration.     

Zur geomorphologischen und geologischen Entwicklungsgeschichte der Ostabdachung der Zentralalpen in der Miozänzeit

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