| 1. |
- Tabiri, S, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 2. |
- Bravo, L, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 3. |
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| 4. |
- Brenninkmeijer, C. A. M., et al.
(författare)
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Civil Aircraft for the regular investigation of the atmosphere based on an instrumented container: The new CARIBIC system
- 2007
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Ingår i: Atmospheric Chemistry and Physics. - 1680-7324. ; 7:18, s. 4953-4976
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Tidskriftsartikel (refereegranskat)abstract
- An airfreight container with automated instruments for measurement of atmospheric gases and trace compounds was operated on a monthly basis onboard a Boeing 767-300 ER of LTU International Airways during long-distance flights from 1997 to 2002 (CARIBIC, Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container, http://www.caribic-atmospheric.com). Subsequently a more advanced system has been developed, using a larger capacity container with additional equipment and an improved inlet system. CARIBIC phase #2 was implemented on a new long-range aircraft type Airbus A340-600 of the Lufthansa German Airlines (Star Alliance) in December 2004, creating a powerful flying observatory. The instrument package comprises detectors for the measurement of O-3, total and gaseous H2O, NO and NOy, CO, CO2, O-2, Hg, and number concentrations of sub-micrometer particles (>4 nm, >12 nm, and >18 nm diameter). Furthermore, an optical particle counter (OPC) and a proton transfer mass spectrometer (PTR-MS) are incorporated. Aerosol samples are collected for analysis of elemental composition and particle morphology after flight. Air samples are taken in glass containers for laboratory analyses of hydrocarbons, halocarbons and greenhouse gases (including isotopic composition of CO2) in several laboratories. Absorption tubes collect oxygenated volatile organic compounds. Three differential optical absorption spectrometers (DOAS) with their telescopes mounted in the inlet system measure atmospheric trace gases such as BrO, HONO, and NO2. A video camera mounted in the inlet provides information about clouds along the flight track. The flying observatory, its equipment and examples of measurement results are reported.
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| 5. |
- Niedermaier, O., et al.
(författare)
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"Safe" Coulomb excitation of Mg-30
- 2005
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 94:17, s. 172501 (artno)-
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Tidskriftsartikel (refereegranskat)abstract
- We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient γ spectrometer MINIBALL. Using Mg-30 ions accelerated to an energy of 2.25 MeV/u together with a thin Ni-nat target, Coulomb excitation of the first excited 2(+) states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation γ-ray yields the B(E2;0(gs)(+)→ 2(1)(+)) value of Mg-30 was determined to be 241(31)e(2) fm(4). Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope Mg-30 resides outside the "island of inversion."
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| 6. |
- Niedermaier, O., et al.
(författare)
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The neutron-rich Mg isotopes: first results from MINIBALL at REX-ISOLDE
- 2005
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 752, s. 273-273
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Tidskriftsartikel (refereegranskat)abstract
- We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient γ spectrometer MINIBALL. Using Mg-30 ions accelerated to an energy of 2.25 MeV/u together with a thin Ni-nat target, Coulomb excitation of the first excited 2(+) states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation γ-ray yields the B(E2;0(gs)(+)→ 2(1)(+)) value of Mg-30 was determined to be 241(31)e(2) fm(4). Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope Mg-30 resides outside the "island of inversion."
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| 7. |
- Scheit, H., et al.
(författare)
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Coulomb excitation of neutron-rich beams at REX-ISOLDE
- 2005
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 25:Suppl. 1, s. 397-402
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Konferensbidrag (refereegranskat)abstract
- After the successful commissioning of the radioactive beam experiment at ISOLDE (REX-ISOLDE) - an accelerator for exotic nuclei produced by ISOLDE - in 2002 and the promotion to a CERN user facility in 2003, first physics experiments using these beams were performed. Initial experiments focused on the region of deformation in the vicinity of the neutron-rich Na and Mg isotopes. Preliminary results on the neutron-rich Na and Mg isotopes show the high potential and physics opportunities offered by the exotic isotope accelerator REX in conjunction with the modern Germanium gamma spectrometer MINIBALL.
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| 8. |
- Michelsen, H. A., et al.
(författare)
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Modeling laser-induced incandescence of soot: a summary and comparison of LII models
- 2007
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Ingår i: Applied Physics B. - : Springer Science and Business Media LLC. - 0946-2171 .- 1432-0649. ; 87:3, s. 503-521
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Tidskriftsartikel (refereegranskat)abstract
- We have performed a comparison of ten models that predict the temporal behavior of laser-induced incandescence (LII) of soot. In this paper we present a summary of the models and comparisons of calculated temperatures, diameters, signals, and energy-balance terms. The models were run assuming laser heating at 532 nm at fluences of 0.05 and 0.70 J/cm(2) with a laser temporal profile provided. Calculations were performed for a single primary particle with a diameter of 30 nm at an ambient temperature of 1800 K and a pressure of 1 bar. Preliminary calculations were performed with a fully constrained model. The comparison of unconstrained models demonstrates a wide spread in calculated LII signals. Many of the differences can be attributed to the values of a few important parameters, such as the refractive-index function E(m) and thermal and mass accommodation coefficients. Constraining these parameters brings most of the models into much better agreement with each other, particularly for the low-fluence case. Agreement among models is not as good for the high-fluence case, even when selected parameters are constrained. The reason for greater variability in model results at high fluence appears to be related to solution approaches to mass and heat loss by sublimation.
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| 9. |
- Borcan, C, et al.
(författare)
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First identification of excited states in the N = Z nucleus Br-70
- 1999
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Ingår i: EUROPEAN PHYSICAL JOURNAL A. - : SPRINGER VERLAG. ; 5:3, s. 243-246
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Excited states in the T-z = 0 nucleus Br-70 have been investigated using the reaction Ni-58(O-16,1p3n). gamma rays were detected with one EUROBALL CLUSTER detector and three single HPGe detectors. Charged particles and neutrons were registered with the Ro
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| 10. |
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| 12. |
- Brack, W., et al.
(författare)
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Strengthen the European collaborative environmental research to meet European policy goals for achieving a sustainable, non-toxic environment
- 2019
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Ingår i: Environmental Sciences Europe. - : Springer Science and Business Media LLC. - 2190-4707 .- 2190-4715. ; 31:1
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Tidskriftsartikel (refereegranskat)abstract
- To meet the United Nations (UN) sustainable development goals and the European Union (EU) strategy for a non-toxic environment, water resources and ecosystems management require cost-efficient solutions for prevailing complex contamination and multiple stressor exposures. For the protection of water resources under global change conditions, specific research needs for prediction, monitoring, assessment and abatement of multiple stressors emerge with respect to maintaining human needs, biodiversity, and ecosystem services. Collaborative European research seems an ideal instrument to mobilize the required transdisciplinary scientific support and tackle the large-scale dimension and develop options required for implementation of European policies. Calls for research on minimizing society's chemical footprints in the water-food-energy-security nexus are required. European research should be complemented with targeted national scientific funding to address specific transformation pathways and support the evaluation, demonstration and implementation of novel approaches on regional scales. The foreseeable pressure developments due to demographic, economic and climate changes require solution-oriented thinking, focusing on the assessment of sustainable abatement options and transformation pathways rather than on status evaluation. Stakeholder involvement is a key success factor in collaborative projects as it allows capturing added value, to address other levels of complexity, and find smarter solutions by synthesizing scientific evidence, integrating governance issues, and addressing transition pathways. This increases the chances of closing the value chain by implementing novel solutions. For the water quality topic, the interacting European collaborative projects SOLUTIONS, MARS and GLOBAQUA and the NORMAN network provide best practice examples for successful applied collaborative research including multi-stakeholder involvement. They provided innovative conceptual, modelling and instrumental options for future monitoring and management of chemical mixtures and multiple stressors in European water resources. Advancement of EU water framework directive-related policies has therefore become an option. Bt Aachen Biol, Aachen, Germany.
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| 16. |
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| 17. |
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| 18. |
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| 19. |
- Ponten, E, et al.
(författare)
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A complex DICER1 syndrome phenotype associated with a germline pathogenic variant affecting the RNase IIIa domain of DICER1
- 2022
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Ingår i: Journal of medical genetics. - : BMJ. - 1468-6244 .- 0022-2593. ; 59:2, s. 141-146
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Tidskriftsartikel (refereegranskat)abstract
- Germline pathogenic variants in DICER1 cause DICER1 syndrome, an autosomal dominant, pleiotropic tumour predisposition syndrome with variable expressivity and reduced penetrance for specific dysplastic and neoplastic lesions. Recently, a syndrome with the acronym GLOW (Global developmental delay, Lung cysts, Overgrowth, Wilms tumour) was described in two children with mosaic missense mutations in hotspot residues of the DICER1 RNase IIIb domain.MethodsWhole genome sequencing, exome sequencing, Sanger sequencing, digital PCR and a review of Wilms tumours with DICER1 RNase III domain mutations were performed.ResultsA de novo heterozygous c.4031C>T (p.S1344L) variant in the sequence encoding the RNase IIIa domain of DICER1 was detected. Clinical investigations revealed a phenotype that resembles the GLOW subphenotype of DICER1 syndrome.ConclusionThe phenotypic overlap between patients with p.S1344L mutation and GLOW syndrome provide clinical support for recent discoveries that RNase IIIa-Ser1344 site mutations impede miRNA-5p biogenesis analogous to DICER1 hotspot mutations in the RNase IIIb domain. We show that an individual with a heterozygous germline p.S1344L mutation has a severe form of DICER1 syndrome (‘DICER1 syndrome plus’), with notable features of intellectual disability, macrocephaly, physical abnormalities, Wilms tumour and a well-differentiated fetal adenocarcinoma of the lung.
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| 20. |
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| 21. |
- Slemr, F., et al.
(författare)
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CARIBIC observations of gaseous mercury in the upper troposphere and lower stratosphere
- 2013
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Ingår i: Proceedings of the 16th International Conference on Heavy Metals in the Environment. - : EDP Sciences. - 2100-014X. ; 1
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Konferensbidrag (refereegranskat)abstract
- A unique set of gaseous mercury measurements in the upper troposphere and lower stratosphere (UT/LS) has been obtained during the monthly CARIBIC (www.caribic-atmospheric.com) flights since May 2005. The passenger Airbus 340-600 of Lufthansa covered routes to the Far East, North America, India, and the southern hemisphere. The accompanying measurements of CO, O3, NOy, H2O, aerosols, halocarbons, hydrocarbons, greenhouse gases, and several other parameters as well as backward trajectories enable a detailed analysis of these measurements. Speciation tests have shown that the CARIBIC measurements represent a good approximation of total gaseous mercury (TGM) concentrations. Above the tropopause TGM always decrease with increasing potential vorticity (PV) and O3 which implies its conversion to particle bound mercury. The observation of the lowest TGM concentrations at the highest particle concentrations in the stratosphere provides further evidence for such conversion. We will show how a seasonally dependent conversion rate could be derived using concomitantly measured SF6 mixing ratios as a timer. Tropospheric mercury data suggest the existence of a decreasing trend in the northern hemisphere whose size is comparable with the trend derived from long-term measurements by ship cruises, at Cape Point (South Africa) and Mace Head (Ireland).
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| 22. |
- Slemr, F., et al.
(författare)
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Gaseous mercury distribution in the upper troposphere and lower stratosphere observed onboard the CARIBIC passenger aircraft
- 2009
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Ingår i: Atmospheric Chemistry and Physics. - 1680-7324. ; 9:6, s. 1957-1969
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Tidskriftsartikel (refereegranskat)abstract
- Total gaseous mercury (TGM) was measured onboard a passenger aircraft during monthly CARIBIC flights (Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrumented Container) made between May 2005 and March 2007 on the routes Frankfurt-Sao Paulo-Santiago de Chile and back and Frankfurt-Guangzhou-Manila and back. The data provide for the first time an insight into the seasonal distributions of TGM in the upper troposphere and lower stratosphere (UT/LS) of both hemispheres and demonstrate the importance of mercury emissions from biomass burning in the Southern Hemisphere. Numerous plumes were observed in the upper troposphere, the larger of which could be characterized in terms of Hg/CO emission ratios and their probable origins. During the flights to China TGM correlated with CO in the upper troposphere with a seasonally dependent slope reflecting the longer lifetime of elemental mercury when compared to that of CO. A pronounced depletion of TGM was always observed in the extratropical lowermost stratosphere. TGM concentrations there were found to decrease with the increasing concentrations of particles. Combined with the large concentrations of particle bond mercury in the stratosphere observed by others, this finding suggests either a direct conversion of TGM to particle bound mercury or an indirect conversion via a semivolatile bivalent mercury compound. Based on concurrent measurements of SF6 during two flights, the rate of this conversion is estimated to 0.4 ng m(-3) yr(-1). A zero TGM concentration was not observed during some 200 flight hours in the lowermost stratosphere suggesting an equilibrium between the gaseous and particulate mercury.
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| 23. |
- Wabo, H., et al.
(författare)
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Constraining the chronology of the mashishing dykes from the eastern kaapvaal craton in South Africa
- 2019
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Ingår i: Springer Geology. - Singapore : Springer Singapore. - 2197-9553 .- 2197-9545. ; , s. 215-261
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Bokkapitel (refereegranskat)abstract
- The present study focuses on NNE-trending dykes (sites LDA to LDJ) that occur near Mashishing in the eastern Kaapvaal craton. The Mashishing dykes were previously considered to be coeval and regarded as the extension of the 1.875–1.835Â Ga Black Hills dyke swarm into the sedimentary rocks of the Pretoria Group. Thin sections exhibit well-preserved igneous textures, with primary minerals (e.g., hornblende, clinopyroxene, plagioclase) extensively altered to secondary minerals in most cases. Our dykes can be petrographically grouped as pyroxenite (LDB and LDC), dolerite (LDH) and diorite (remainder of samples). REE and multi-element profiles of pyroxenites and two of the diorites (LDI and LDJ) suggest a common origin of the four dykes, but show no similarity with known mafic units of the Kaapvaal craton. An age estimate between 2208 and 2276Â Ma for dyke LDB, obtained from two overlapping amphibole 40Ar/39Ar plateau results, indicates that these four dykes predates the ~2.05Â Ga Bushveld event. The six remaining dykes have similar chemistry to either the ~2.06Â Ga Dullstroom Lavas (LDG), the 1.875–1.835Â Ga Black Hills dyke swarm (LDH) or the ~1.11Â Ga Umkondo dolerites (LDA, LDD, LDE and LDF). An U–Pb baddeleyite date of 1867 ± 10Â Ma for dyke LDH confirms it as a member of the Black Hills dyke swarm. Demagnetization of eighty-three specimens reveals five stable magnetizations carried by titanomagnetite. Two of these are regarded as magnetic overprints while three magnetizations are likely representative of primary remanences. The corresponding virtual geomagnetic poles (Lat.−26.84°N, Long. 31.66°E; Lat. 26.07°N, Long. 11.01°E, and Lat. 55.84°N, Long. 65.02°E) resemble those from the ~2.23Â Ga Hekpoort Formation, the ~1.88–1.83Â Ga post-Waterberg intrusions, and the ~1.11Â Ga Umkondo dolerites respectively. The above results suggest that the Mashishing dykes, despite similar trends, constitute swarms of different generations.
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| 24. |
- Wabo, H., et al.
(författare)
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New U–Pb age and paleomagnetic constraints from the Uitkomst Complex, South Africa : clues to the timing of intrusion
- 2016
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Ingår i: GFF. - : Informa UK Limited. - 1103-5897 .- 2000-0863. ; 138:1, s. 152-163
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Tidskriftsartikel (refereegranskat)abstract
- The Uitkomst Complex is considered to be coeval with, and genetically linked to the Rustenburg Layered Suite (RLS) of the Bushveld Large Igneous Province. This study reports new paleomagnetic, geochemical and geochronological results from the Uitkomst Complex and a crosscutting dyke at the Nkomati Mine. Primary magnetisations for the complex and the dyke are statistically indistinguishable. This, together with the geochemical signature of the dyke, suggests a late-magmatic link with the Uitkomst Complex. A Virtual Geomagnetic Pole calculated for the complex at Longitude 28.7°N and Latitude 58.5°E (dp = 6.2; dm = 9.4; N = 3) differs from the 1900 Ma and younger-aged poles for the Kaapvaal Craton. It, however, shares similarities with the poles from the 2058 to 2054 Ma RLS and other ~2.0 Ga paleopoles for the Kaapvaal Craton. Moreover, a new U–Pb baddeleyite age of 2054 ± 7 Ma given by a coarse-grained gabbroic sample from Nkomati’s underground mine provides a minimum age constraint on the crystallisation of the Uitkomst Complex. This date is nominally older than the 207Pb/206Pb zircon age of 2044 ± 8 Ma previously reported for this complex, and also near identical to the new age of 2054.89 ± 0.37 Ma from the Critical Zone of the RLS. Here, it is suggested that the Uitkomst Complex was emplaced at the same time as, if not before the Critical Zone. Data presented here have bearings on the location of the Uitkomst Complex in the time frame model recently proposed for the Bushveld magmatism.
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| 25. |
- Wilson, Samuel T., et al.
(författare)
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Ideas and perspectives : A strategic assessment of methane and nitrous oxide measurements in the marine environment
- 2020
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 17:22, s. 5809-5828
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Tidskriftsartikel (refereegranskat)abstract
- In the current era of rapid climate change, accurate characterization of climate-relevant gas dynamics – namely production, consumption, and net emissions – is required for all biomes, especially those ecosystems most susceptible to the impact of change. Marine environments include regions that act as net sources or sinks for numerous climate-active trace gases including methane (CH4) and nitrous oxide (N2O). The temporal and spatial distributions of CH4 and N2O are controlled by the interaction of complex biogeochemical and physical processes. To evaluate and quantify how these mechanisms affect marine CH4 and N2O cycling requires a combination of traditional scientific disciplines including oceanography, microbiology, and numerical modeling. Fundamental to these efforts is ensuring that the datasets produced by independent scientists are comparable and interoperable. Equally critical is transparent communication within the research community about the technical improvements required to increase our collective understanding of marine CH4 and N2O. A workshop sponsored by Ocean Carbon and Biogeochemistry (OCB) was organized to enhance dialogue and collaborations pertaining to marine CH4 and N2O. Here, we summarize the outcomes from the workshop to describe the challenges and opportunities for near-future CH4 and N2O research in the marine environment.
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| 26. |
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