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Berlin Brandenburg

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  • MEDLINE/PubMed (NLM)  (29)
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  • 1
    Language: English
    In: Brain Topography, 2012, Vol.25(4), pp.423-430
    Description: Music is capable of inducing emotional arousal. While previous studies used brief musical excerpts to induce one specific emotion, the current study aimed to identify the physiological correlates of continuous changes in subjective emotional states while listening to a complete music piece. A total of 19 participants listened to the first movement of Ludwig van Beethoven’s 5th symphony (duration: ~7.4 min), during which a continuous 76-channel EEG was recorded. In a second session, the subjects evaluated their emotional arousal during the listening. A fast fourier transform was performed and covariance maps of spectral power were computed in association with the subjective arousal ratings. Subjective arousal ratings had good inter-individual correlations. Covariance maps showed a right-frontal suppression of lower alpha-band activity during high arousal. The results indicate that music is a powerful arousal-modulating stimulus. The temporal dynamics of the piece are well suited for sequential analysis, and could be necessary in helping unfold the full emotional power of music.
    Keywords: Arousal ; Emotion ; Music ; EEG ; Frontal alpha-asymmetry
    ISSN: 0896-0267
    E-ISSN: 1573-6792
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  • 2
    In: Psychophysiology, September 2013, Vol.50(9), pp.909-919
    Description: The present study investigates the relation of perceived arousal (continuous self‐rating), autonomic nervous system activity (heart rate, heart rate variability) and musical characteristics (sound intensity, musical rhythm) upon listening to a complex musical piece. Twenty amateur musicians listened to two performances of hopin's “Tristesse” with different rhythmic shapes. Besides conventional statistical methods for analyzing psychophysiological reactions (heart rate, respiration rate) and musical variables, semblance analysis was used. Perceived arousal correlated strongly with sound intensity; heart rate showed only a partial response to changes in sound intensity. Larger changes in heart rate were caused by the version with more rhythmic tension. The low‐/high‐frequency ratio of heart rate variability increased—whereas the high frequency component decreased—during music listening. We conclude that autonomic nervous system activity can be modulated not only by sound intensity but also by the interpreter's use of rhythmic tension. Semblance analysis enables us to track the subtle correlations between musical and physiological variables.
    Keywords: Music ; Subjective Arousal ; Sound Intensity ; Heart Rate ; Heart Rate Variability ; Respiration Rate ; Tempo Rubato ; Semblance Analysis
    ISSN: 0048-5772
    E-ISSN: 1469-8986
    E-ISSN: 15405958
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  • 3
    Language: English
    In: Environmental science & technology, 15 November 2011, Vol.45(22), pp.9550-7
    Description: Formation of ternary complexes between arsenic (As) oxyanions and ferric iron (Fe) complexes of humic substances (HS) is often hypothesized to represent a major mechanism for As-HS interactions under oxic conditions. However, direct evidence for this potentially important binding mechanism is still lacking. To investigate the molecular-scale interaction between arsenate, As(V), and HS in the presence of Fe(III), we reacted fulvic and humic acids with Fe(III) (1 wt %) and equilibrated the Fe(III)-HS complexes formed with As(V) at pH 7 (molar Fe/As ~10). The local (〈5 Å) coordination environments of As and Fe were subsequently studied by means of X-ray absorption spectroscopy. Our results show that 4.5-12.5 μmol As(V)/g HS (25-70% of total As) was associated with Fe(III). At least 70% of this As pool was bound to Fe(III)-HS complexes via inner-sphere complexation. Results obtained from shell fits of As K-edge extended X-ray absorption fine structure (EXAFS) spectra were consistent with a monodentate binuclear ((2)C) and monodentate mononuclear ((1)V) complex stabilized by H-bonds (R(As-Fe) = 3.30 Å). The analysis of Fe K-edge EXAFS spectra revealed that Fe in Fe(III)-HS complexes was predominantly present as oligomeric Fe(III) clusters at neutral pH. Shell-fit results complied with a structural motif in which three corner-sharing Fe(O,OH)(6) octahedra linked by a single μ(3)-O bridge form a planar Fe trimer. In these complexes, the average Fe-C and Fe-Fe bond distances were 2.95 Å and 3.47 Å, respectively. Our study provides the first spectroscopic evidence for ternary complex formation between As(V) and Fe(III)-HS complexes, suggesting that this binding mechanism is of fundamental importance for the cycling of oxyanions such as As(V) in organic-rich, oxic soils and sediments.
    Keywords: Arsenates -- Chemistry ; Ferric Compounds -- Chemistry ; Humic Substances -- Analysis
    ISSN: 0013936X
    E-ISSN: 1520-5851
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  • 4
    Language: English
    In: Environmental Science and Technology, 01 April 2016, Vol.50(8)
    Description: Here, peatlands have received significant atmospheric inputs of As and S since the onset of the Industrial Revolution, but the effect of S deposition on the fate of As is largely unknown. It may encompass the formation of As sulfides and organosulfur-bound As, or the indirect stimulation of As biotransformation processes, which are presently not considered as important As immobilization pathways in wetlands. To investigate the immobilization mechanisms of anthropogenically derived As in peatlands subjected to long-term atmospheric pollution, we explored the solid-phase speciation of As, Fe, and S in English peat bogs by X-ray absorption spectroscopy. Additionally, we analyzed the speciation of As in pore- and streamwaters. Linear combination fits of extended X-ray absorption fine structure (EXAFS) data imply that 62–100% (average: 82%) of solid-phase As (Astot: 9–92 mg/kg) was present as organic As(V) and As(III). In agreement with appreciable concentrations of organoarsenicals in surface waters (pH: 4.0–4.4, Eh: 165–190 mV, average Astot: 1.5–129 μg/L), our findings reveal extensive biotransformation of atmospheric As and the enrichment of organoarsenicals in the peat, suggesting that the importance of organometal(loid)s in wetlands subjected to prolonged air pollution is higher than previously assumed.
    Keywords: Environmental Sciences ; Engineering ; Environmental Sciences
    ISSN: 0013-936X
    E-ISSN: 1520-5851
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  • 5
    Language: English
    In: Environmental science & technology, 18 February 2014, Vol.48(4), pp.2281-9
    Description: Organosulfur-coordinated As(III) and realgar (α-As4S4) have been identified as the dominant As species in the naturally As-enriched minerotrophic peatland Gola di Lago, Switzerland. In this study, we explored their oxidation kinetics in peat exposed to atmospheric O2 for up to 180 days under sterile and nonsterile conditions (25 °C, ∼ 100% relative humidity). Anoxic peat samples were collected from a near-surface (0-38 cm) and a deep peat layer (200-250 cm) and studied by bulk As, Fe, and S K-edge X-ray absorption spectroscopy as well as selective extractions as a function of time. Over 180 days, only up to 33% of organosulfur-coordinated As(III) and 44% of realgar were oxidized, corresponding to half-life times, t1/2, of 312 and 215 days, respectively. The oxidation of both As species was mainly controlled by abiotic processes. Realgar was oxidized orders of magnitude slower than predicted from published mixed-flow reactor experiments, indicating that mass-transfer processes were rate-limiting. Most of the As released (〉97%) was sequestered by Fe(III)-(hydr)oxides. However, water-extractable As reached concentrations of 0.7-19 μmol As L(-1), exceeding the WHO drinking water limit by up to 145 times. Only a fraction (20-36%) of reduced S(-II to I) was sensitive to oxidation and was oxidized faster (t1/2 = 50-173 days) than organosulfur-coordinated As(III) and realgar, suggesting a rapid loss of reactive As-sequestering S species following a drop in the water table. Our results imply that wetlands like Gola di Lago can serve as long-term sources for As under prolonged oxidizing conditions. The maintenance of reducing conditions is thus regarded as the primary strategy in the management of this and other As-rich peatlands.
    Keywords: Arsenic -- Chemistry ; Arsenicals -- Chemistry ; Soil -- Chemistry ; Sulfides -- Chemistry ; Sulfur Compounds -- Chemistry
    ISSN: 0013936X
    E-ISSN: 1520-5851
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  • 6
    Language: English
    In: Environmental science & technology, 07 October 2014, Vol.48(19), pp.11320-9
    Description: Elevated solution concentrations of As in anoxic natural systems are usually accompanied by microbially mediated As(V), Mn(III/IV), and Fe(III) reduction. The microbially mediated reductive dissolution of Fe(III)-(oxyhydr)oxides mainly liberates sorbed As(V) which is subsequently reduced to As(III). Manganese oxides have been shown to rapidly oxidize As(III) and Fe(II) under oxic conditions, but their net effect on the microbially mediated reductive release of As and Fe is still poorly understood. Here, we investigated the microbial reduction of As(V)-bearing ferrihydrite (molar As/Fe: 0.05; Fe tot: 32.1 mM) by Shewanella sp. ANA-3 (10(8) cells/mL) in the presence of different concentrations of birnessite (Mn tot: 0, 0.9, 3.1 mM) at circumneutral pH over 397 h using wet-chemical analyses and X-ray absorption spectroscopy. Additional abiotic experiments were performed to explore the reactivity of birnessite toward As(III) and Fe(II) in the presence of Mn(II), Fe(II), ferrihydrite, or deactivated bacterial cells. Compared to the birnessite-free control, the highest birnessite concentration resulted in 78% less Fe and 47% less As reduction at the end of the biotic experiment. The abiotic oxidation of As(III) by birnessite (k initial = 0.68 ± 0.31/h) was inhibited by Mn(II) and ferrihydrite, and lowered by Fe(II) and bacterial cell material. In contrast, the oxidation of Fe(II) by birnessite proceeded equally fast under all conditions (k initial = 493 ± 2/h) and was significantly faster than the oxidation of As(III). We conclude that in the presence of birnessite, microbially produced Fe(II) is rapidly reoxidized and precipitates as As-sequestering ferrihydrite. Our findings imply that the ability of Mn-oxides to oxidize As(III) in water-logged soils and sediments is limited by the formation of ferrihydrite and surface passivation processes.
    Keywords: Arsenic -- Chemistry ; Ferric Compounds -- Chemistry ; Iron -- Chemistry ; Oxides -- Chemistry ; Shewanella -- Metabolism
    ISSN: 0013936X
    E-ISSN: 1520-5851
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  • 7
    Language: English
    In: Environmental science & technology, 2013, Vol.47(21), pp.12165-73
    Description: The speciation of As in wetlands is often controlled by natural organic matter (NOM), which can form strong complexes with Fe(III). Here, we elucidated the molecular-scale interaction of arsenite (As(III)) with Fe(III)-NOM complexes under reducing conditions. We reacted peat (40-250 μm size fraction, 1.0 g Fe/kg) with 0-15 g Fe/kg at pH 〈2, removed nonreacted Fe, and subsequently equilibrated the Fe(III) complexes formed with 900 mg As/kg peat at pH 7.0, 8.4, and 8.8. The solid-phase speciation of Fe and As was studied by electron paramagnetic resonance (Fe) and X-ray absorption spectroscopy (As, Fe). Our results show that the majority of Fe in the peat was present as mononuclear Fe(III) species (RFe-C = 2.82-2.88 Å), probably accompanied by small Fe(III) clusters of low nuclearity (RFe-Fe = 3.25-3.46 Å) at high pH and elevated Fe contents. The amount of As(III) retained by the original peat was 161 mg As/kg, which increased by up to 250% at pH 8.8 and an Fe loading of 7.3 g/kg. With increasing Fe content of peat, As(III) increasingly formed bidentate mononuclear (RAs-Fe = 2.88-2.94 Å) and monodentate binuclear (RAs-Fe = 3.35-3.41 Å) complexes with Fe, thus yielding direct evidence of ternary complex formation. The ternary complex formation went along with a ligand exchange reaction between As(III) and hydroxylic/phenolic groups of the peat (RAs-C = 2.70-2.77 Å). Our findings thus provide spectroscopic evidence for two yet unconfirmed As(III)-NOM interaction mechanisms, which may play a vital role in the cycling of As in sub- and anoxic NOM-rich environments such as peatlands, peaty sediments, swamps, or rice paddies.
    Keywords: Arsenites -- Metabolism ; Ferric Compounds -- Chemistry ; Soil -- Chemistry ; Soil Pollutants -- Metabolism
    ISSN: 0013936X
    E-ISSN: 1520-5851
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  • 8
    Language: English
    In: Environmental science & technology, 01 April 2014, Vol.48(7), pp.3822-31
    Description: Binding of arsenite (As(III)) to sulfhydryl groups (Sorg(-II)) plays a key role in As detoxification mechanisms of plants and microorganisms, As remediation techniques, and reduced environmental systems rich in natural organic matter. Here, we studied the formation of Sorg(-II)-As(III) complexes on a sulfhydryl model adsorbent (Ambersep GT74 resin) in the absence and presence of ferrihydrite as a competing mineral adsorbent under reducing conditions and tested their stability against oxidation in air. Adsorption of As(III) onto the resin was studied in the pH range 4.0-9.0. On the basis of As X-ray absorption spectroscopy (XAS) results, a surface complexation model describing the pH dependence of As(III) binding to the organic adsorbent was developed. Stability constants (log K) determined for dithio ((AmbS)2AsO(-)) and trithio ((AmbS)3As) surface complexes were 8.4 and 7.3, respectively. The ability of sulfhydryl ligands to compete with ferrihydrite for As(III) was tested in various anoxic mixtures of both adsorbents at pH 7.0. At a 1:1 ratio of their reactive binding sites, R-SH and ≡FeOH, both adsorbents possessed nearly identical affinities for As(III). The oxidation of Sorg(-II)-As(III) complexes in water vapor saturated air over 80 days, monitored by As and S XAS, revealed that the complexed As(III) is stabilized against oxidation (t1/2 = 318 days). Our results thus document that sulfhydryl ligands are highly competitive As(III) complexing agents that can stabilize As in its reduced oxidation state even under prolonged oxidizing conditions. These findings are particularly relevant for organic S-rich semiterrestrial environments subject to periodic redox potential changes such as peatlands, marshes, and estuaries.
    Keywords: Models, Theoretical ; Arsenites -- Chemistry ; Ferric Compounds -- Chemistry ; Sulfhydryl Compounds -- Chemistry
    ISSN: 0013936X
    E-ISSN: 1520-5851
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  • 9
    Language: English
    In: Environmental Science and Technology, 06 September 2016, Vol.50(17)
    Description: Reductive release of the potentially toxic metalloid As from Fe(III) (oxyhydr)oxides has been identified as an important process leading to elevated As porewater concentrations in soils and sediments. Despite the ubiquitous presence of Mn oxides in soils and their oxidizing power toward As(III), their impact on interrelated As, Fe, and Mn speciation under microbially reducing conditions remains largely unknown. For this reason, we employed a column setup and X-ray absorption spectroscopy to investigate the influence of increasing birnessite concentrations (molar soil Fe-to-Mn ratios: 4.8, 10.2, and 24.7) on As speciation and release from an As-contaminated floodplain soil (214 mg As/kg) under anoxic conditions. Our results show that birnessite additions significantly decreased As leaching. The reduction of both As and Fe was delayed, and As(III) accumulated in birnessite-rich column parts, indicating the passivation of birnessite and its transformation products toward As(III) oxidation and the precipitation of Fe(III)(oxyhydr)oxides. Microbial Mn reduction resulted in elevated soil pH values, which in turn lowered the microbial activity in the birnessite-enriched soil. We conclude that in Mn-oxide-rich soil environments undergoing redox fluctuations, the enhanced As adsorption to newly formed Fe(III) (oxyhydr)oxides under reducing conditions leads to a transient stabilization of As.
    Keywords: Engineering ; Environmental Sciences
    ISSN: 0013-936X
    E-ISSN: 1520-5851
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  • 10
    Language: English
    In: Environmental science & technology, 06 November 2012, Vol.46(21), pp.11788-97
    Description: Terrestrial ecosystems rich in natural organic matter (NOM) can act as a sink for As. Recently, the complexation of trivalent As by sulfhydryl groups of NOM was proposed as the main mechanism for As-NOM interactions in anoxic S- and NOM-rich environments. Here we tested the molecular-scale interaction of bisulfide (S(-II)) with NOM and its consequences for arsenite (As(III)) binding. We reacted 0.2 mol C/L peat and humic acid (HA) with up to 5.8 mM S(-II) at pH 7 and 5, respectively, and subsequently equilibrated the reaction products with 55 μM As(III) under anoxic conditions. The speciation of S and the local coordination environment of As in the solid phase were studied by X-ray absorption spectroscopy. Our results document a rapid reaction of S(-II) with peat and HA and the concomitant formation of reduced organic S species. These species were highly reactive toward As(III). Shell fits of As K-edge extended X-ray absorption fine structure spectra revealed that the coordination environment of trivalent As was progressively occupied by S atoms. Fitted As-S distances of 2.24-2.34 Å were consistent with sulfhydryl-bound As(III). Besides As(III) complexation by organic monosulfides, our data suggests the formation of nanocrystalline As sulfide phases in HA samples and an As sorption process for both organic sorbents in which As(III) retained its first-shell oxygens. In conclusion, this study documents that S(-II) reaction with NOM can greatly enhance the ability of NOM to bind As in anoxic environments.
    Keywords: Humic Substances ; Arsenites -- Chemistry ; Soil -- Chemistry ; Soil Pollutants -- Chemistry ; Sulfides -- Chemistry
    ISSN: 0013936X
    E-ISSN: 1520-5851
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