| 1. |
- Ahlström, Lars-Henric, et al.
(författare)
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Application of standard addition methodology for the determination of banned azo dyes in different leather types
- 2005
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Ingår i: Analytica Chimica Acta. - : Elsevier BV. - 1873-4324 .- 0003-2670. ; 552:1-2, s. 76-80
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Tidskriftsartikel (refereegranskat)abstract
- An analytical procedure based on microwave-assisted extraction (MAE) and standard addition was applied for the determination of banned azo dyes in bovine, sheep, and goat leather. Standard addition at four different concentration levels was performed using azo dyes, dissolved either in methanol or water. All dyes were determined indirectly by measuring their corresponding harmful aromatic amines, formed after reduction by use of sodium dithionite. Comparing found amounts of amines with theoretical target values allowed an assessment of accuracy. The recoveries were also compared with those obtained for non-spiked samples using external standard calibration. The standard addition approaches provided much better accuracy than external standard calibration, with recoveries close to 100% for most amines. Since there was no great difference in recoveries when using methanol or water as solvent, preparation of the dyes in methanol might be preferred because of the faster evaporation of the solvent after spiking. (c) 2005 Elsevier B.V. All rights reserved.
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| 2. |
- Raab, Juraj, et al.
(författare)
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A combined experimental and theoretical study of uranium polyhydrides with new evidence for the large complex UH4(H-2)(6)
- 2007
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Ingår i: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 111:28, s. 6383-6387
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Tidskriftsartikel (refereegranskat)abstract
- Several monouranium and diuranium polyhydride molecules were investigated using quantum chemical methods. The infrared spectra of uranium and hydrogen reaction products in condensed neon and pure hydrogen were measured and compared with previous argon matrix frequencies. The calculated molecular structures and vibrational frequencies were used to identify the species present in the matrix. Major new absorptions were observed and compared with the previous argon matrix study. Spectroscopic evidence was obtained for the novel complex, UH4(H-2)(6), which has potential interest as a metal hydride with a large number of hydrogen atoms bound to uranium. Our calculations show that the series of complexes UH4(H-2)(1,2,4,6) are stable.
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| 3. |
- Raab, Juraj, et al.
(författare)
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Excitation energies for transition metal atoms - A comparison between coupled cluster methods and second-order perturbation theory
- 2005
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Ingår i: Advances in Quantum Chemistry. - 0065-3276. ; 48, s. 421-433
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Forskningsöversikt (refereegranskat)abstract
- Coupled cluster methods are compared to multiconfigurational second-order perturbation theory in a study of the high spin d(x)s(2) -> d(x+1)s(1) excitations in first, second, and third row transition metals. Large basis sets of the atomic natural orbital type are used. Scalar relativistic effects are included using the Douglas-Kroll-Hess Hamiltonian. The effect of spin-orbit coupling is demonstrated for third row atoms. The results show that the two methods give results of the same accuracy, with the exception of first row atoms with less than five 3d-electrons. The CASPT2 method here overestimates the effect of 3p correlation with about 0.1 eV.
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| 4. |
- Yefanov, Oleksandr, et al.
(författare)
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Evaluation of serial crystallographic structure determination within megahertz pulse trains
- 2019
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Ingår i: Structural Dynamics. - : AMER INST PHYSICS. - 2329-7778. ; 6:6
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Tidskriftsartikel (refereegranskat)abstract
- The new European X-ray Free-Electron Laser (European XFEL) is the first X-ray free-electron laser capable of delivering intense X-ray pulses with a megahertz interpulse spacing in a wavelength range suitable for atomic resolution structure determination. An outstanding but crucial question is whether the use of a pulse repetition rate nearly four orders of magnitude higher than previously possible results in unwanted structural changes due to either radiation damage or systematic effects on data quality. Here, separate structures from the first and subsequent pulses in the European XFEL pulse train were determined, showing that there is essentially no difference between structures determined from different pulses under currently available operating conditions at the European XFEL.
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