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| 3. |
- Barucca, G., et al.
(författare)
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The potential of Λ and Ξ- studies with PANDA at FAIR
- 2021
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Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 57:4
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Tidskriftsartikel (refereegranskat)abstract
- The antiproton experiment PANDA at FAIR is designed to bring hadron physics to a new level in terms of scope, precision and accuracy. In this work, its unique capability for studies of hyperons is outlined. We discuss ground-state hyperons as diagnostic tools to study non-perturbative aspects of the strong interaction, and fundamental symmetries. New simulation studies have been carried out for two benchmark hyperon-antihyperon production channels: p¯ p→ Λ¯ Λ and p¯ p→ Ξ¯ +Ξ-. The results, presented in detail in this paper, show that hyperon-antihyperon pairs from these reactions can be exclusively reconstructed with high efficiency and very low background contamination. In addition, the polarisation and spin correlations have been studied, exploiting the weak, self-analysing decay of hyperons and antihyperons. Two independent approaches to the finite efficiency have been applied and evaluated: one standard multidimensional efficiency correction approach, and one efficiency independent approach. The applicability of the latter was thoroughly evaluated for all channels, beam momenta and observables. The standard method yields good results in all cases, and shows that spin observables can be studied with high precision and accuracy already in the first phase of data taking with PANDA.
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| 4. |
- Barucca, G., et al.
(författare)
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Study of excited Ξ baryons with the P¯ ANDA detector
- 2021
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Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 57:4
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Tidskriftsartikel (refereegranskat)abstract
- The study of baryon excitation spectra provides insight into the inner structure of baryons. So far, most of the world-wide efforts have been directed towards N∗ and Δ spectroscopy. Nevertheless, the study of the double and triple strange baryon spectrum provides independent information to the N∗ and Δ spectra. The future antiproton experiment P¯ANDA will provide direct access to final states containing a Ξ¯ Ξ pair, for which production cross sections up to μb are expected in p¯p reactions. With a luminosity of L= 10 31 cm- 2 s- 1 in the first phase of the experiment, the expected cross sections correspond to a production rate of ∼106events/day. With a nearly 4 π detector acceptance, P¯ANDA will thus be a hyperon factory. In this study, reactions of the type p¯p → Ξ¯ +Ξ∗ - as well as p¯p → Ξ¯ ∗ +Ξ- with various decay modes are investigated. For the exclusive reconstruction of the signal events a full decay tree fit is used, resulting in reconstruction efficiencies between 3 and 5%. This allows high statistics data to be collected within a few weeks of data taking.
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| 6. |
- Mayes, Maureen D, et al.
(författare)
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Immunochip analysis identifies multiple susceptibility Loci for systemic sclerosis.
- 2014
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Ingår i: American Journal of Human Genetics. - : Elsevier BV. - 0002-9297 .- 1537-6605. ; 94:1, s. 47-61
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Tidskriftsartikel (refereegranskat)abstract
- In this study, 1,833 systemic sclerosis (SSc) cases and 3,466 controls were genotyped with the Immunochip array. Classical alleles, amino acid residues, and SNPs across the human leukocyte antigen (HLA) region were imputed and tested. These analyses resulted in a model composed of six polymorphic amino acid positions and seven SNPs that explained the observed significant associations in the region. In addition, a replication step comprising 4,017 SSc cases and 5,935 controls was carried out for several selected non-HLA variants, reaching a total of 5,850 cases and 9,401 controls of European ancestry. Following this strategy, we identified and validated three SSc risk loci, including DNASE1L3 at 3p14, the SCHIP1-IL12A locus at 3q25, and ATG5 at 6q21, as well as a suggested association of the TREH-DDX6 locus at 11q23. The associations of several previously reported SSc risk loci were validated and further refined, and the observed peak of association in PXK was related to DNASE1L3. Our study has increased the number of known genetic associations with SSc, provided further insight into the pleiotropic effects of shared autoimmune risk factors, and highlighted the power of dense mapping for detecting previously overlooked susceptibility loci.
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- Lundstedt, Staffan, et al.
(författare)
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First intercomparison study on the analysis of oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs) and nitrogen heterocyclic polycyclic aromatic compounds (N-PACs) in contaminated soil
- 2014
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Ingår i: TrAC. Trends in analytical chemistry. - : Elsevier. - 0165-9936 .- 1879-3142. ; 57, s. 83-92
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Forskningsöversikt (refereegranskat)abstract
- Oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs) and nitrogen heterocyclic polycyclic aromatic compounds (N-PACs) are toxic, highly leachable and often abundant at sites that are also contaminated with PAHs. However, due to lack of regulations and standardized methods for their analysis, they are seldom included in monitoring and risk-assessment programs. This intercomparison study constitutes an important step in the harmonization of the analytical methods currently used, and may also be considered a first step towards the certification of reference materials for these compounds. The results showed that the participants were able to determine oxy-PAHs with accuracy similar to PAHs, with average determined mass fractions agreeing well with the known levels in a spiked soil and acceptable inter- and intra-laboratory precisions for all soils analyzed. For the N-PACs, the results were less satisfactory, and have to be improved by using analytical methods more specifically optimized for these compounds.
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| 10. |
- Saketkoo, LA, et al.
(författare)
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World Health Organization (WHO) International Classification of Functioning, Disability and Health (ICF) Core Set Development for Interstitial Lung Disease
- 2022
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Ingår i: Frontiers in pharmacology. - : Frontiers Media SA. - 1663-9812. ; 13, s. 979788-
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Tidskriftsartikel (refereegranskat)abstract
- Background: The World Health Organization (WHO) introduced the International Classification of Functioning, Disability, and Health (ICF) as a scientific method of disability data collection comprised of >1,200 categories describing the spectrum of impairment types (functional, symptoms-based and anatomical) under the bio-psycho-social model with consideration of environmental and personal factors (pf). ICF Core Sets and ICF Checklists are streamlined disease-specific resources for clinical use, service provision, and for use in health economics and health policy. ICF can disclose strengths and weaknesses across multiple patient-reported outcome measures (PROMs) and help consolidate best-fitting question-items from multiple PROMs. Interstitial lung diseases (ILDs), are generally progressive, with restrictive physiology sometimes occurring in the context of multi-organ autoimmunity/inflammatory conditions such as connective tissue diseases (CTDs). In spite of significant associated morbidity and potential disability, ILD has yet to be linked to the ICF.Methods: Each instrument and their question-items within the consensus-recommended core sets for clinical trials in ILD were deconstructed to single concept units, and then linked per updated ICF linkage rules. Inter-linker agreement was established. Three additional subsequently validated measures were also included.Results: One-hundred-eleven ICF categories were identified for ten PROMs and three traditional objective measures that were amenable to ICF linkage. The proportion of agreement ranged from 0.79 (95% CI: 0.62, 0.91) to 0.93 (0.76, 0.99) with the overall proportion of inter-linker agreement being very high 0.86 (0.82, 0.89) for the initial instruments, with 94–100% for the three additional PROMs. Thirty-four new ‘Personal Factors’ emerged to capture disease-specific qualities not elsewhere described in ICF, e.g. ‘pf_embarrassed by cough’ or ‘pf_panic/afraid when can’t get a breath’.Conclusion: This first known effort in ICF linkage of ILD has provided important revelations on the current utility of the ICF in lung disease. Results have indicated areas for meaningful assessment of ICF descriptors for lung impairment. The mapping across PROMs provides insight into possibilities of developing more streamline and precise instrumentation. Finally, familiarity with the ICF in ILD may enable clinicians to experience a smoother transition with the imminent harmonization of ICD and ICF, ICD-11.
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| 11. |
- Szefer, P, et al.
(författare)
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Heavy-metal pollution of sediments from the Polish exclusive economic zone, southern Baltic Sea
- 2009
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Ingår i: Environmental Geology. - Berlin / Heidelberg : Springer. - 0943-0105 .- 1432-0495. ; 57:4, s. 847-862
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Tidskriftsartikel (refereegranskat)abstract
- Analysis of 59 surface sediment samples from the Polish exclusive economic zone (EEZ) shows that Szczecin Lagoon sediments are the most polluted by heavy metals and that the degree of heavy-metal pollution decreases substantially on passing from the Szczecin Lagoon to the Pomeranian Bay and the inner shelf area and then on passing to the Bornholm Deep and Słupsk Furrow. Heavy-metal pollution in the sediments of the western part of the Polish EEZ therefore appears to follow the dispersion of the Oder River. Fluffy material from the Oder estuary appears to be the main source of heavy metals in the muddy sediments of the Bornholm Deep. The formation of sulphides is therefore not the principal factor controlling the enrichment of heavy metals in the sediments of this anoxic basin, although it may be responsible for the uptake of Mo, Sb and As. Two main factors control the distribution of the rare earth elements (REE) in sediments of the Polish EEZ: the input of Fe-organic colloids from rivers and the presence of detrital material in the sediments.
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| 15. |
- Kumar, Sunil J., et al.
(författare)
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A simple method for synthesis of organotin species to investigate extraction procedures in sediments by isotope dilution-gas chromatography-inductively coupled plasma mass spectrometry : Part 2. Phenyltin species
- 2004
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Ingår i: Journal of Analytical Atomic Spectrometry. - London : Royal Society of Chemistry. - 0267-9477 .- 1364-5544. ; 19:3, s. 368-372
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Tidskriftsartikel (refereegranskat)abstract
- A rapid method for the synthesis of phenyltin species based on the phenylation of tin iodide was developed and a standard of 124Sn, enriched monophenyltin (MPhT), diphenyltin (DPhT) and triphenyltin (TPhT) was produced. Isotope enriched species were added to and equilibrated with the certified reference material BCR 646 to evaluate different extraction procedures currently in use for the determination of organic tin species in sediments. Samples were measured by gas chromatography-inductively coupled plasma mass spectrometry (GC-ICP-MS) with species specific isotope dilution (SSID) calibration. For TPhT measurement results agreed with the certified values for extraction methods using tropolone in diethyl ether alone or in the presence of NaCl and HCl as well as with 50% HBr. However, with 50% HBr, concentrations obtained for DPhT and MPhT were above the upper limit (2) of the certification. The stability of phenyltin species was studied by comparing their signal magnitudes in spike solutions generated directly after derivatisation with those obtained after applying the extraction–derivatisation procedures. Degradation of phenyltin species was matrix dependent and appeared for most of the extraction methods investigated. For water standards and BCR 646, extraction with methanol combined with dichloromethane or methanol combined with acetic acid gave no degradation when applied with less than 20 min ultrasonication. Extraction efficiencies for these two methods were however low for the BCR 646 matrix, in particular for DPhT and MPhT.
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| 16. |
- Lambertsson, Lars, et al.
(författare)
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Rapid dissolution of cinnabar in crude oils at reservoir temperatures facilitated by reduced Sulfur Ligands
- 2018
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Ingår i: ACS Earth and Space Chemistry. - : American Chemical Society (ACS). - 2472-3452. ; 2:10, s. 1022-1028
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Tidskriftsartikel (refereegranskat)abstract
- Mercury (Hg) is present in petrochemical samples, including crude oils, and the processing and use of petroleum products contribute to global Hg emissions. We present a refined theory on geochemical processes controlling Hg concentrations in crude oil by studying dissolution kinetics and solubility thermodynamics of cinnabar (α-HgS(s)) in different crude oils held at reservoir temperatures. In a black light crude oil, α-HgS(s) dissolved in an apparent zero-order reaction with a rate of 0.14−0.58 μmoles m−2 s −1 at 170−230 °C and an estimated activation energy of 43 kJ mol−1 . For crude oil samples with a total sulfur concentration spanning 0.15− 2.38% (w/w), the measured dissolution rate varied between 0.05 and 0.24 μmoles m−2 s−1 at 200 °C. Separate tests showed that thiols and, to a lesser extent, organic sulfides increased the solubility of α-HgS(s) in isooctane at room temperature compared to thiophenes, disulfides, and elemental sulfur. Long-term (14 days) α-HgS(s) solubility tests in a crude oil at 200 °C generated dissolved Hg concentrations in the 0.3% (w/w) range. The high α-HgS(s) dissolving capacity of the crude oils was more than 2 orders of magnitude greater than the highest reported Hg concentration in crude oils globally. On the basis of the kinetic and solubility data, it was further concluded that α-HgS(s) is not stable under typical petroleum reservoir conditions and would decompose to elemental mercury (Hg0 ). Our results suggest that source/reservoir temperature, abundance of reduced sulfur compounds in the crude oil, and dissolved Hg0 evasion processes are principal factors controlling the ultimate Hg concentration in a specific crude oil deposit.
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| 17. |
- Matousek, T, et al.
(författare)
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Gas flow patterns and longitudinal distribution of free selenium atoms in quartz tube atomizers for hydride generation atomic absorption spectrometry
- 2000
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Ingår i: Spectrochimica Acta Part B: Atomic Spectroscopy. ; 55:2, s. 151-63
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Tidskriftsartikel (refereegranskat)abstract
- Gas flow patterns in unheated quartz tube hydride atomizers were studied by light scattering on ammonium chloride particles and by observation of iodine vapors. The flow pattern is basically laminar, with a turbulent region at the T-junction and irregularities at the tube ends. We studied the free atom distribution over the length of the atomizers optical bar under various conditions by measuring the selenium signal with the tube perpendicular to the radiation beam, through the tube walls. In the whole range of atomization conditions used (Se 60-400 g l-1, 0.8-2 l min-1 of H2 as purge gas, 0-50 ml min-1 O2,), there is a sharp maximum of free atom concentration in the tube centre, and all the free atoms disappear before they reach the tube ends. The absorption profiles are essentially the same in unheated as in flame-heated tubes, and there is no difference between heated flame-in-tube and externally heated arrangement. With decreasing purge gas flow rate, free atoms occupy a shorter part of the tube. Free atoms start to decay immediately after entering the optical tube of the atomizer. In both heated and unheated atomizers, enhanced free atom decay at higher concentrations contributes to the curvature of calibration graphs. As all free atoms disappear before reaching the ends of the tube even at relatively high purge gas flow rates, it is not possible to obtain higher sensitivities by extending the atomizer length. There is no difference in the free atom distribution in the central part of the tube if oxygen is prevented to enter the tube from the ends (by quartz windows or flames burning at the tube ends), so the free atom decay is not caused by O2 diffusing from the ambient atmosphere. With flames burning on tube ends, free Se atoms were reappearing close to the ends, proving the possibility of reatomization of species formed by free atom reactions. When no measures against O2 penetration from the tube ends of the heated atomizer are taken, signal reappearance takes place at the borders of the hot part of the atomizer, contributing substantially to the overall sensitivity. The results obtained correspond very well to the present picture of hydride atomization by H-radicals and their subsequent decay.
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| 18. |
- Qian, J, et al.
(författare)
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Efficiency of solvent extraction methods for the determination of methyl mercury in forest soils.
- 2000
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Ingår i: Fresenius J Anal Chem. - 0937-0633. ; 367:5, s. 467-73
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Tidskriftsartikel (refereegranskat)abstract
- Methyl mercury was determined by gas chromatography, microwave induced plasma, atomic emission spectrometry (GC-MIP-AES) using two different methods. One was based on extraction of mercury species into toluene, pre-concentration by evaporation and butylation of methyl mercury with a Grignard reagent followed by determination. With the other, methyl mercury was extracted into dichloromethane and back extracted into water followed by in situ ethylation, collection of ethylated mercury species on Tenax and determination. The accuracy of the entire procedure based on butylation was validated for the individual steps involved in the method. Methyl mercury added to various types of soil samples showed an overall average recovery of 87.5%. Reduced recovery was only caused by losses of methyl mercury during extraction into toluene and during pre-concentration by evaporation. The extraction of methyl mercury added to the soil was therefore quantitative. Since it is not possible to directly determine the extraction efficiency of incipient methyl mercury, the extraction efficiency of total mercury with an acidified solution containing CuSO4 and KBr was compared with high-pressure microwave acid digestion. The solvent extraction efficiency was 93%. For the IAEA 356 sediment certified reference material, mercury was less efficiently extracted and determined methyl mercury concentrations were below the certified value. Incomplete extraction could be explained by the presence of a large part of inorganic sulfides, as determined by x-ray absorption near-edge structure spectroscopy (XANES). Analyses of sediment reference material CRM 580 gave results in agreement with the certified value. The butylation method gave a detection limit for methyl mercury of 0.1 ng g(-1), calculated as three times the standard deviation for repeated analysis of soil samples. Lower values were obtained with the ethylation method. The precision, expressed as RSD for concentrations 20 times above the detection limit, was typically 5%.
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| 20. |
- Skyllberg, U, et al.
(författare)
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Combined XANES and EXAFS study on the bonding of methyl mercury to thiol groups in soil and aquatic organic matter
- 2005
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Ingår i: Physica Scripta. - : The Royal Swedish Academy of Sciences. ; T115, s. 894-6
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Tidskriftsartikel (refereegranskat)abstract
- We combined x-ray absorption near edge spectroscopy (XANES) and extended x-ray absorption fine structure (EXAFS) spectroscopy to determine the coordination chemistry of methyl mercury (CH3Hg) in natural organic matter from an organic soil (OS), potentially soluble organic matter extracted from the soil (PSOS) and in a humic stream draining the soil (SOS). The sum of concentrations of highly reduced organic S groups (Org-SRED), such as thiol (RSH), sulfide (RSR) and disulphide (RSSR) was 39, 42 and 47% of total S in SOS, PSOS and OS, respectively. No traces of inorganic sulfides were detected. Hg LIII-edge EXAFS analysis were determined on samples added CH3Hg to yield CH3Hg/Org-SRED ratios in the range 0.01-1.62. At low ratios Hg was associated to one C atom (the methyl-group) at an average distance of 2.03 ± 0.02 Å and to one S atom at an average distance of 2.34 ± 0.03 Å in the first coordination shell. At higher CH3Hg/Org-SRED ratios RSH groups were saturated and O and/or N atoms gradually took part in the bonding. Based on the assumption that RSH is the only S group accounting for the very strong complexation of CH3Hg, approximately 17% of total organic S consisted of RSH groups in the organic soil, 14% in potentially soluble organic matter extracted from soil and 9% in aquatic organic matter.
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