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Institution

University of Bremen

EducationBremen, Germany
About: University of Bremen is a education organization based out in Bremen, Germany. It is known for research contribution in the topics: Population & Glacial period. The organization has 14563 authors who have published 37279 publications receiving 970381 citations. The organization is also known as: Universität Bremen.


Papers
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Journal ArticleDOI
TL;DR: In this paper, a review analyzes and summarizes the results obtained to date by a significant number of research groups on the micelle formation of imidazolium ILs in an aqueous solution, including the phenomena observed.

342 citations

Journal ArticleDOI
TL;DR: In this paper, the authors re-estimate the modern global fluviatile organic carbon discharge-and burial rates and find that approximately 430×1012 g of terrestrial organic carbon are transported to the ocean in modern times.
Abstract: This study re-estimates one important component in the global carbon cycle: the modern global fluviatile organic carbon discharge- and burial rates. According to these results, approximately 430×1012 g of terrestrial organic carbon are transported to the ocean in modern times. This amount is higher than the latest estimates but takes into account new data from Oceania not previously considered in global flux studies. However, only the minor amount of 10% or approximately 43×1012 gC year–1 is most likely buried in marine sediments. This amount is similar to the burial of marine organic carbon in the coastal ocean (55×1012 gC year–1). Adding both estimates gives approximately 100×1012 gC year–1, which is the value calculated by Berner (1982) for "terrestrial" deltaic-shelf sediments. However, the results in this study suggest that on a global scale the organic carbon content in coastal ocean sediments is not solely of terrestrial origin but a mixture of nearly equal amounts of marine and terrestrial organic carbon. The major part of the terrestrial organic carbon that enters the ocean by rivers (approximately 400×1012 gC year–1) seems to be either (a) remineralised in the ocean, whereas the mechanism by which the terrestrial organic carbon is oxidised in the ocean are unknown; or (b) is dispersed throughout the oceans and accumulates in pelagic sediments.

342 citations

Journal ArticleDOI
TL;DR: The importance of band gap energy in the phototoxic response of the cell to TiO(2) nanoparticles is demonstrated and the potential of this material to generate adverse effects in humans and the environment during high-intensity light exposure is reflected.
Abstract: UV-light-induced electron–hole (e–/h+) pair generation with free radical production in TiO2-based nanoparticles is a major conceptual paradigm for biological injury. However, to date, this hypothesis has been difficult to experimentally verify due to the high energy of UV light that is intrinsically highly toxic to biological systems. Here, a versatile flame spray pyrolysis (FSP) synthetic process has been exploited to synthesize a library of iron-doped (0–10 wt%) TiO2 nanoparticles. These particles have been tested for photoactivation-mediated cytotoxicity using near-visible light exposure. The reduction in TiO2 band gap energy with incremental levels of Fe loading maintained the nanoparticle crystalline structure in spite of homogeneous Fe distribution (demonstrated by XRD, HRTEM, SAED, EFTEM, and EELS). Photochemical studies showed that band gap energy was reciprocally tuned proportional to the Fe content. The photo-oxidation capability of Fe-doped TiO2 was found to increase during near-visible light e...

341 citations

Journal ArticleDOI
21 Oct 1999-Nature
TL;DR: This paper used a sediment core from the western North Atlantic Ocean to show that two-thirds of the carbon-isotope anomaly occurred within no more than a few thousand years, indicating that carbon was catastrophically released into the ocean and atmosphere.
Abstract: Current models of the global carbon cycle lack natural mechanisms to explain known large, transient shifts in past records of the stable carbon-isotope ratio (δ13C) of carbon reservoirs1,2. The injection into the atmosphere of ∼1,200–2,000 gigatons of carbon, as methane from the decomposition of sedimentary methane hydrates, has been proposed to explain a δ13C anomaly3,4 associated with high-latitude warming1 and changes in marine5,6,7 and terrestrial8 biota near the Palaeocene–Eocene boundary, about 55 million years ago. These events may thus be considered as a natural ‘experiment’ on the effects of transient greenhouse warming. Here we use physical, chemical and spectral analyses of a sediment core from the western North Atlantic Ocean to show that two-thirds of the carbon-isotope anomaly occurred within no more than a few thousand years, indicating that carbon was catastrophically released into the ocean and atmosphere. Both the δ13C anomaly and biotic changes began between 54.93 and 54.98 million years ago, and are synchronous in oceans and on land. The longevity of the δ13C anomaly suggests that the residence time of carbon in the Palaeocene global carbon cycle was ∼120 thousand years, which is similar to the modelled response after a massive input of methane3,4. Our results suggest that large natural perturbations to the global carbon cycle have occurred in the past—probably by abrupt failure of sedimentary carbon reservoirs—at rates that are similar to those induced today by human activity.

340 citations

Journal ArticleDOI
22 Dec 2000-Science
TL;DR: A deep-sea sediment core underlying the Benguela upwelling system off southwest Africa provides a continuous time series of sea surface temperature (SST) for the past 4.5 million years, indicating that temperatures in the region have declined by about 10 degrees C since 3.2 million years ago.
Abstract: A deep-sea sediment core underlying the Benguela upwelling system off southwest Africa provides a continuous time series of sea surface temperature (SST) for the past 4.5 million years. Our results indicate that temperatures in the region have declined by about 10°C since 3.2 million years ago. Records of paleoproductivity suggest that this cooling was associated with an increase in wind-driven upwelling tied to a shift from relatively stable global warmth during the mid-Pliocene to the high-amplitude glacial-interglacial cycles of the late Quaternary. These observations imply that Atlantic Ocean surface water circulation was radically different during the mid-Pliocene.

340 citations


Authors

Showing all 14961 results

NameH-indexPapersCitations
Roger Y. Tsien163441138267
Klaus-Robert Müller12976479391
Ron Kikinis12668463398
Ulrich S. Schubert122222985604
Andreas Richter11076948262
Michael Böhm10875566103
Juan Bisquert10745046267
John P. Sumpter10126646184
Jos Lelieveld10057037657
Michael Schulz10075950719
Peter Singer9470237128
Charles R. Tyler9232531724
John P. Burrows9081536169
Hans-Peter Kriegel8944473932
Harald Haas8575034927
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
2023343
2022709
20212,106
20202,309
20192,191
20181,965