| 1. |
- Wikberg, Elena, et al.
(författare)
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Calibration Method for the Determination of the FAME and HVO Contents in Fossil Diesel Blends Using NIR Spectroscopy
- 2021
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Ingår i: Fuels. - : MDPI AG. - 2673-3994. ; 2:2, s. 179-193
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Tidskriftsartikel (refereegranskat)abstract
- The European diesel fuel standard, EN590, allows a 7% (V/V) biodiesel (FAME) addition to automotive diesel fuel. The allowed addition of renewable diesel (HVO) to fossil diesel is not defined, as long as the properties of the fuel blend still meet the requirements of the standard. However, it is important to analyze the biofuels’ content in diesel fuel blends. In this article, a development procedure of a calibration method for quantification of the HVO and FAME contents in fossil diesel blends using near-infrared (NIR) spectroscopy is presented. The analytical range of quantification of biodiesel content is from 0 to 10% (V/V) and of renewable diesel content from 0 to 20% (V/V). The partial least squares (PLS) regression method for multivariable data analysis and construction of the calibration models were used to create the calibration method. The constructed PLS models obtained prediction results for all diesel fuel blends with root mean square error of prediction (RMSEP) values of 2.66% (V/V) for the HVO content quantification and 0.18% (V/V) for quantification of the FAME content. This article concludes that the calibration method is acceptable for laboratory applications in practice.
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| 2. |
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| 3. |
- Alekseev, Anton, et al.
(författare)
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Provenance of classical Hamiltonian time crystals
- 2020
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Ingår i: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; :8
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Tidskriftsartikel (refereegranskat)abstract
- Classical Hamiltonian systems with conserved charges and those with constraints often describe dynamics on a pre-symplectic manifold. Here we show that a pre-symplectic manifold is also the proper stage to describe autonomous energy conserving Hamiltonian time crystals. We explain how the occurrence of a time crystal relates to the wider concept of spontaneously broken symmetries; in the case of a time crystal, the symmetry breaking takes place in a dynamical context. We then analyze in detail two examples of timecrystalline Hamiltonian dynamics. The first example is a piecewise linear closed string, with dynamics determined by a Lie-Poisson bracket and Hamiltonian that relates to membrane stability. We explain how the Lie-Poisson brackets descents to a time-crystalline pre-symplectic bracket, and we show that the Hamiltonian dynamics supports two phases; in one phase we have a time crystal and in the other phase time crystals are absent. The second example is a discrete one dimensional model of a Hamiltonian chain. It is obtained by a reduction from the Q-ball Lagrangian that describes time dependent nontopological solitons. We show that a time crystal appears as a minimum energy domain wall configuration, along the chain.
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| 4. |
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| 5. |
- Begun, A., et al.
(författare)
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Gauge theory : protein topology and dynamics
- 2018
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Ingår i: Journal of Bioenergetics and Biomembranes. - : SPRINGER/PLENUM PUBLISHERS. - 0145-479X .- 1573-6881. ; 50:6, s. 500-501
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 6. |
- Begun, Alexander, et al.
(författare)
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On topology and knotty entanglement in protein folding
- 2021
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 16:1
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Tidskriftsartikel (refereegranskat)abstract
- We investigate aspects of topology in protein folding. For this we numerically simulate the temperature driven folding and unfolding of the slipknotted archaeal virus protein AFV3-109. Due to knottiness the (un)folding is a topological process, it engages the entire backbone in a collective fashion. Accordingly we introduce a topological approach to model the process. Our simulations reveal that the (un)folding of AFV3-109 slipknot proceeds through a folding intermediate that has the topology of a trefoil knot. We observe that the final slipknot causes a slight swelling of the folded AFV3-109 structure. We disclose the relative stability of the strands and helices during both the folding and unfolding processes. We confirm results from previous studies that pointed out that it can be very demanding to simulate the formation of knotty self-entanglement, and we explain how the problems are circumvented: The slipknotted AFV3-109 protein is a very slow folder with a topologically demanding pathway, which needs to be properly accounted for in a simulation description. When we either increase the relative stiffness of bending, or when we decrease the speed of ambient cooling, the rate of slipknot formation rapidly increases.
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| 7. |
- Begun, Alexander, et al.
(författare)
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Protein tertiary structure and the myoglobin phase diagram
- 2019
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- We develop an effective theory approach to investigate the phase properties of globular proteins. Instead of interactions between individual atoms or localized interaction centers, the approach builds directly on the tertiary structure of a protein. As an example we construct the phase diagram of (apo) myoglobin with temperature (T) and acidity (pH) as the thermodynamical variables. We describe how myoglobin unfolds from the native folded state to a random coil when temperature and acidity increase. We confirm the presence of two molten globule folding intermediates, and we predict an abrupt transition between the two when acidity changes. When temperature further increases we find that the abrupt transition line between the two molten globule states terminates at a tricritical point, where the helical structures fade away. Our results also suggest that the ligand entry and exit is driven by large scale collective motions that destabilize the myoglobin F-helix.
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| 8. |
- Cederlöf, Erik, et al.
(författare)
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Antipsychotic medications and sleep problems in patients with schizophrenia
- 2024
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Ingår i: Schizophrenia Research. - : Elsevier. - 0920-9964 .- 1573-2509. ; 267, s. 230-238
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Tidskriftsartikel (refereegranskat)abstract
- Background: Sleep problems are common and related to a worse quality of life in patients with schizophrenia. Almost all patients with schizophrenia use antipsychotic medications, which usually increase sleep. Still, the differences in subjective sleep outcomes between different antipsychotic medications are not entirely clear.Methods: This study assessed 5466 patients with schizophrenia and is part of the nationwide Finnish SUPER study. We examined how the five most common antipsychotic medications (clozapine, olanzapine, quetiapine, aripiprazole, and risperidone) associate with questionnaire-based sleep problems in logistic regression analyses, including head-to-head analyses between different antipsychotic medications. The sleep problems were difficulties initiating sleep, early morning awakenings, fatigue, poor sleep quality, short (≤6 h) and long sleep duration (≥10 h).Results: The average number of antipsychotic medications was 1.59 per patient. Clozapine was associated with long sleep duration (49.0 % of clozapine users vs 30.2 % of other patients, OR = 2.05, 95 % CI 1.83–2.30, p < .001). Olanzapine and risperidone were in head-to-head analyses associated with less sleep problems than patients using aripiprazole, quetiapine, or no antipsychotic medication. Aripiprazole and quetiapine were associated with more insomnia symptoms and poorer sleep quality. Patients without antipsychotic medications (N = 159) had poorer sleep quality than patients with antipsychotic use, and short sleep duration was common (21.5 % of patients using antipsychotics vs 7.8 % of patients using antipsychotics, OR = 2.97, 95 % CI 1.98–4.44, p < .001).Conclusions: Prevalence of sleep problems is markedly related to the antipsychotic medication the patient uses. These findings underline the importance of considering and assessing sleep problems when treating schizophrenia patients with antipsychotics.
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| 9. |
- Chen, Si, et al.
(författare)
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On Ramachandran angles, closed strings and knots in protein structure
- 2016
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Ingår i: Journal of Physics D. - : IOP Publishing. - 0022-3727 .- 1361-6463. ; 49:31
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Tidskriftsartikel (refereegranskat)abstract
- The Ramachandran angles (phi, psi) of a protein backbone form the vertices of a piecewise geodesic curve on the surface of a torus. When the ends of the curve are connected to each other similarly, by a geodesic, the result is a closed string that in general wraps around the torus a number of times both in the meridional and the longitudinal directions. The two wrapping numbers are global characteristics of the protein structure. A statistical analysis of the wrapping numbers in terms of crystallographic x-ray structures in the protein data bank (PDB) reveals that proteins have no net chirality in the phi direction but in the psi direction, proteins prefer to display chirality. A comparison between the wrapping numbers and the concept of folding index discloses a non-linearity in their relationship. Thus these three integer valued invariants can be used in tandem, to scrutinize and classify the global loop structure of individual PDB proteins, in terms of the overall fold topology.
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| 10. |
- Chernodub, M. N., et al.
(författare)
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Baryon number violation and a new electroweak interaction
- 2009
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Ingår i: Physical Review D. - 1550-7998. ; 79:7, s. 077901-
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Tidskriftsartikel (refereegranskat)abstract
- We introduce a new supercurrent in the electroweak sector of the standard model. Its interaction with the hypergauge field influences the mass of the Z boson but has no effect on the W-+/- boson masses. In the leptonic sector it affects the numerical value of the vector and axial coupling constants between neutral currents and the Z boson, and a comparison with experimental values yields an upper bound to the strength of the coupling between the supercurrent and the hypergauge field. In the baryonic sector the supercurrent gives a new contribution to the anomaly equation for baryon number current. As a consequence it may have an effect on baryogenesis.
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