Kooperativer Bibliotheksverbund

Berlin Brandenburg

and
and

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Type of Medium
Language
Year
  • 1
    Language: English
    In: Vadose Zone Journal, 2015, Vol.14(4), p.0
    Description: Recent advances in wireless sensor technology allow monitoring of soil moisture dynamics with high temporal resolution at varying spatial scales. The objectives of this study were to: (i) develop an efficient strategy for monitoring soil moisture dynamics at the hillslope scale using a wireless sensor network; and (ii) characterize spatial patterns of soil moisture and infer hydrological processes controlling the dynamics of such patterns, using a method of analysis that allows the identification of the relevant hydrological dynamics within large data sets. We combined soil hydrological and pedological expertise with geophysical measurements and methods from digital soil mapping for designing the monitoring setup for a grassland hillslope in the Schafertal catchment, central Germany. Hypothesizing a wet and a dry soil moisture state to be characteristic of the spatial pattern of soil moisture, we described the spatial and temporal evolution of such patterns using a method of analysis based on the Spearman rank correlation coefficient. We described the persistence and switching mechanisms of the two characteristic states, inferring the local properties that control the observed spatial patterns and the hydrological processes driving the transitions. The spatial organization of soil moisture appears to be controlled by different processes in different soil horizons, and the topsoil's moisture does not mirror processes that take place within the soil profile. The results will help to improve conceptual understanding for hydrological model studies at similar or smaller scales and to transfer observation concepts and process understanding to larger or less instrumented areas.
    Keywords: Soils ; Hydrogeology ; Central Europe ; Central Germany ; Characterization ; Diurnal Variations ; Drainage Basins ; Dynamics ; Electromagnetic Induction ; Europe ; Evapotranspiration ; Field Studies ; Gamma-Ray Spectra ; Germany ; Grain Size ; Harz Mountains ; Hydrology ; Latin Hypercube Sampling ; Mechanism ; Moisture ; Monitoring ; Sampling ; Saxony-Anhalt Germany ; Scale Factor ; Schafertal Basin ; Size Distribution ; Slopes ; Soil Profiles ; Soil Surveys ; Soils ; Spatial Distribution ; Spectra ; Surveys ; Tanner ; Temporal Distribution ; Topography ; Unsaturated Zone;
    ISSN: Vadose Zone Journal
    E-ISSN: 1539-1663
    Source: CrossRef
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
  • 3
  • 4
    Language: English
    In: Geoscientific Instrumentation, Methods and Data Systems, 2018, Vol.7(1), pp.83-99
    Description: Sensor-to-sensor variability is a source of error common to all geoscientific instruments that needs to be assessed before comparative and applied research can be performed with multiple sensors. Consistency among sensor systems is especially critical when subtle features of the surrounding terrain are to be identified. Cosmic-ray neutron sensors (CRNSs) are a recent technology used to monitor hectometre-scale environmental water storages, for which a rigorous comparison study of numerous co-located sensors has not yet been performed. In this work, nine stationary CRNS probes of type “CRS1000” were installed in relative proximity on a grass patch surrounded by trees, buildings, and sealed areas. While the dynamics of the neutron count rates were found to be similar, offsets of a few percent from the absolute average neutron count rates were found. Technical adjustments of the individual detection parameters brought all instruments into good agreement. Furthermore, we found a critical integration time of 6 h above which all sensors showed consistent dynamics in the data and their RMSE fell below 1 % of gravimetric water content. The residual differences between the nine signals indicated local effects of the complex urban terrain on the scale of several metres. Mobile CRNS measurements and spatial simulations with the URANOS neutron transport code in the surrounding area (25 ha) have revealed substantial sub-footprint heterogeneity to which CRNS detectors are sensitive despite their large averaging volume. The sealed and constantly dry structures in the footprint furthermore damped the dynamics of the CRNS-derived soil moisture. We developed strategies to correct for the sealed-area effect based on theoretical insights about the spatial sensitivity of the sensor. This procedure not only led to reliable soil moisture estimation during dry-out periods, it further revealed a strong signal of intercepted water that emerged over the sealed surfaces during rain events. The presented arrangement offered a unique opportunity to demonstrate the CRNS performance in complex terrain, and the results indicated great potential for further applications in urban climate research.
    Keywords: Urban Environments ; Monitoring Instruments ; Gravimetry ; Sensors ; Surfaces ; Soil Moisture ; Environmental Monitoring ; Environmental Monitoring ; Water Content ; Water Balance ; Water Balance ; Sensors ; Soil Moisture ; Spatial Discrimination ; Moisture Content ; Instruments ; Offsets ; Research ; Water Balance ; Moisture ; Cosmic Rays ; Urban Areas ; Error Detection ; Water Content ; Detectors ; Dynamics ; Heterogeneity ; Soil Moisture ; Sensors ; Sensors ; Footprints ; Intercomparison ; Soil Dynamics ; Detection ; Soils ; Terrain ; Water Content ; Water Balance;
    ISSN: Geoscientific Instrumentation, Methods and Data Systems
    ISSN: 21930856
    E-ISSN: 2193-0864
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Language: English
    In: Environmental Earth Sciences, 2017, Vol.76(1), pp.1-25
    Description: This article provides an overview about the Bode River catchment that was selected as the hydrological observatory and main region for hydro-ecological research within the TERrestrial ENvironmental Observatories Harz/Central German Lowland Observatory. It first provides information about the general characteristics of the catchment including climate, geology, soils, land use, water quality and aquatic ecology, followed by the description of the interdisciplinary research framework and the monitoring concept with the main components of the multi-scale and multi-temporal monitoring infrastructure. It also shows examples of interdisciplinary research projects aiming to advance the understanding of complex hydrological processes under natural and anthropogenic forcings and their interactions in a catchment context. The overview is complemented with research work conducted at a number of intensive research sites, each focusing on a particular functional zone or specific components and processes of the hydro-ecological system.
    Keywords: Monitoring ; Catchment ; Water quality ; Observatory ; Water fluxes
    ISSN: 1866-6280
    E-ISSN: 1866-6299
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Language: English
    In: FEBS Letters, 07 May 2012, Vol.586(9), pp.1363-1369
    Description: ► Biomechanical load of the heart causes ER stress. ► Preload alone does not suffice to cause ER stress. ► Additional elevation in afterload is necessary to induce ER stress. ► The role of afterload could be demonstrated in vitro and in vivo. ► Angiotensin II is only partially responsible for the afterload-induced ER stress. Proteins are folded in the endoplasmic reticulum (ER). ER stress initially leads to compensatory upregulation of ER chaperones and later to apoptosis, but the contribution of biomechanical load vs. neurohumoral stress to myocardial ER stress is unknown. We show that the ER chaperones Grp78 and calreticulin (CRT) are upregulated by afterload, but not by preload in vitro and in vivo. Angiotensin II upregulated ER chaperones in unloaded muscle strips, but the angiotensin receptor-1 antagonist irbesartan did not significantly blunt the induction of ER chaperones by afterload. In monocrotaline-treated rats, Grp78 and CRT were upregulated in the afterloaded right ventricle, but not in the only neurohumorally stressed left ventricle. These findings suggest that afterload but not preload induces myocardial ER stress, largely independent of angiotensin II signaling.
    Keywords: Er Stress ; Preload ; Afterload ; Angiotensin ; Biology ; Chemistry ; Anatomy & Physiology
    ISSN: 0014-5793
    E-ISSN: 1873-3468
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Language: English
    In: The journal of physical chemistry. C, Nanomaterials and interfaces, 29 August 2013, Vol.117(34), pp.17666-17673
    Description: In situ FT-IR spectroscopy was exploited to study the adsorption of CO and CO on commercially available yttria-stabilized ZrO (8 mol % Y, YSZ-8), YO, and ZrO. All three oxides were pretreated at high temperatures (1173 K) in air, which leads to effective dehydroxylation of pure ZrO. Both YO and YSZ-8 show a much higher reactivity toward CO and CO adsorption than ZrO because of more facile rehydroxylation of Y-containing phases. Several different carbonate species have been observed following CO adsorption on YO and YSZ-8, which are much more strongly bound on the former, due to formation of higher-coordinated polydentate carbonate species upon annealing. As the crucial factor governing the formation of carbonates, the presence of reactive (basic) surface hydroxyl groups on Y-centers was identified. Therefore, chemisorption of CO most likely includes insertion of the CO molecule into a reactive surface hydroxyl group and the subsequent formation of a bicarbonate species. Formate formation following CO adsorption has been observed on all three oxides but is less pronounced on ZrO due to effective dehydroxylation of the surface during high-temperature treatment. The latter generally causes suppression of the surface reactivity of ZrO samples regarding reactions involving CO or CO as reaction intermediates.
    Keywords: Article;
    ISSN: 1932-7447
    E-ISSN: 19327455
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Language: English
    In: The Journal of Physical Chemistry C, 02/25/2016, Vol.120(7), pp.3882-3898
    Description: The C1-surface chemistry of catalytically and technologically relevant oxides (YSZ, ZrO2, and Y2O3) toward CH4, CO, and CO2 was comparatively studied by electrochemical impedance (EIS) and spectroscopic (FT-IR) methods. Highly correlated in situ measurements yield a consistent picture with respect to qualitative and quantitative surface modifications as a function of temperature and gas phase composition. This includes not only a detailed study of carbon deposition in methane and adsorption of CO and CO2 but also proof of the strong influence of surface chemistry. On all studied oxides, carbon deposited during methane treatment grows dynamically forming interconnected islands and eventually a continuous conducting carbon layer at T ≥ 1073 K. Before methane dissociation via gas phase radical reactions/H-abstraction and carbon growth, a complex redox interplay of total oxidation as well as formate and carbonate formation leads to associated surface and grain conductivity changes. For CO adsorption, these measurements yield data on the time and temperature dependence of the adsorbate- and carburization-induced conductivity processes. In that respect, an equivalent circuit model in dry CO allows to disentangle the different contributions of grain interiors, grain boundaries, and electrode contributions. For YSZ, temperature regions with different charge carrier activation energies could be identified, perfectly corresponding to significant changes in surface chemistry. Hydroxyl groups, carbonates, or formates strongly influence the impedance properties, suggesting that the conductivity properties of YSZ, e.g., in a realistic reforming gas mixture, cannot be reduced to exclusive bulk ion conduction. Because of the different degree of hydroxylation and the different ability to chemisorb CO and CO2, the influence of the surface chemistry on the electrochemical properties is varying strongly: in contrast to ZrO2, the impact of the studied C1-gases on YSZ and Y2O3 is substantial. This also includes the reoxidation/reactivation behavior of the surfaces.
    Keywords: Carbon ; Methane ; Zirconium:IV:Oxide ; Oxide ; Carbonates ; Adsorbate ; Dissociation ; Gaseous-Phase-Reaction ; Total-Oxidation ; Surface-Chemistry ; Reactivity ; Surface-Conductivity ; Temporal-Dependence ; Carbonate-Coating ; Measured-Value ; GAS-Mixtures ; Ion-Conductivity ; Reoxidation ; Kohlenstoff ; Methan ; Zro2 ; Oxid ; Carbonat ; Adsorbat ; Dissoziation ; Gasphasenreaktion ; Totaloxidation ; Oberflächenchemie ; Chemisches Reaktionsvermögen ; Oberflächenleitfähigkeit ; Zeitabhängigkeit ; Carbonatschicht ; Messdaten ; Gasgemisch ; Ionenleitung ; Reoxidation ; Chemistry;
    ISSN: 1932-7447
    E-ISSN: 1932-7455
    Source: American Chemical Society (via CrossRef)
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Language: English
    In: The Journal of Physical Chemistry C, 10/06/2016, Vol.120(39), pp.22443-22454
    Description: The C1 chemistry of Y-doped ZrO2 samples (3, 8, 20, and 40 mol% Y2O3; 3-YSZ, 8-YSZ, 20-YSZ, and 40-YSZ) was comparatively studied with respect to the correlation of electrochemical properties and surface chemistry in CH4, CO, and CO2 atmospheres by electrochemical impedance (EIS) and spectroscopic (FT-IR) methods up to 1273 K to unravel the influence of the Y-doping level. A consistent picture with respect to qualitative and quantitative surface modifications as a function of temperature and gas-phase composition evolves by performing highly correlated operando/in situ measurements. A detailed study of carbon deposition in CH4 and CO and adsorption of CO and CO2, but also proof of the strong influence of the surface chemistry, is included. Carbon deposition during treatment in CH4 and CO at temperatures T ≥ 1023 K is a common feature on all materials, irrespective of the Y content. On the 40-YSZ sample, the thinnest, but at the same time fully percolated, carbon layer was generated, and hence, "metallic" conductivity was apparent. This goes along with the fact that 40-YSZ is most unreactive toward adsorption, suggesting a direct link between homogeneous deposition and suppressed reactivity. For all Y-doped samples, temperature regions with different charge carrier activation energies could be identified, perfectly corresponding to significant changes in surface chemistry. Due to the different degree of hydroxylation and the different ability to chemisorb CO and CO2, the influence of the surface chemistry on the electrochemical properties is varying strongly as a function of Y-content.
    Keywords: Kohlenstoff ; Oberflächenchemie ; Zro2 ; Chemisches Reaktionsvermögen ; Struktur-Eigenschaft-Beziehung ; Gaszusammensetzung ; Phasendiagramm ; Chemistry;
    ISSN: 1932-7447
    E-ISSN: 1932-7455
    Source: American Chemical Society (via CrossRef)
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    In: Physical Chemistry Chemical Physics, 2016, Vol.18(38), pp.26873-26884
    Description: Two mixed ionicelectronic conducting, Fe-containing perovskites were investigated regarding their reducibility in dry H 2 , namely lanthanum strontium ferrite (LSF4, La 0.6 Sr 0.4 FeO 3 ) and strontium titanium ferrite (STF3, SrTi 0.7 Fe 0.3 O 3 ). Upon treatment under comparable reduction conditions, LSF4 is by far more affected by reduction and is reduced more deeply than STF3. Thermal treatments of fully oxidized or slightly reduced LSF4/STF3 at decreased O 2 partial pressure lead to spontaneous desorption of O 2 . Temperature-programmed desorption (TPD) spectra of H 2 reveal distinct differences in H 2 and H 2 O desorption. A simple mass balance of H 2 reveals that oxygen vacancies formed on STF3 are more resilient towards O 2 re-oxidation compared to those on LSF4. The results also imply that substantial amounts of hydrogen are dissolved in the bulk of LSF4 or STF3. 4.9 10 2 mol H 2 per mol LSF4 and 1.6 10 2 mol H 2 per mol STF3 are incorporated if the specimens are heated in flowing/dry H 2 up to 550 C and 612 C, respectively. For LSF4 this equals about 13 hypothetical ML of H 2 and for STF3 about 20 hypothetical ML of H 2 . This conclusion is also supported by Fourier-transform infrared spectroscopy (FT-IR). FT-IR reveals water formation during static H 2 treatment of LSF4/STF3, which indicates perovskite reduction. Furthermore, both samples behave extraordinarily hydrophobic and no chemistry involving surface hydroxy groups was observed.
    Keywords: Perovskite ; Strontium-Ferrite ; Lanthanum ; Oxygen ; Heat-Treatment ; Desorption ; Partial-Pressure ; Mass-Balance ; Hydrogen ; Infrared-Spectrometry ; Perowskit ; Strontiumferrit ; Lanthan ; Sauerstoff ; Thermische Behandlung ; Desorption ; Partialdruck ; Massenbilanz ; Wasserstoff ; Infrarotspektroskopie ; Chemistry;
    ISSN: 1463-9076
    E-ISSN: 1463-9084
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages