| 1. |
- Lappalainen, Hanna K., et al.
(author)
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Pan-Eurasian Experiment (PEEX) : towards a holistic understanding of the feedbacks and interactions in the land-atmosphere-ocean-society continuum in the northern Eurasian region
- 2016
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In: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 16:22, s. 14421-14461
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Journal article (peer-reviewed)abstract
- The northern Eurasian regions and Arctic Ocean will very likely undergo substantial changes during the next decades. The Arctic-boreal natural environments play a crucial role in the global climate via albedo change, carbon sources and sinks as well as atmospheric aerosol production from biogenic volatile organic compounds. Furthermore, it is expected that global trade activities, demographic movement, and use of natural resources will be increasing in the Arctic regions. There is a need for a novel research approach, which not only identifies and tackles the relevant multi-disciplinary research questions, but also is able to make a holistic system analysis of the expected feedbacks. In this paper, we introduce the research agenda of the Pan-Eurasian Experiment (PEEX), a multi-scale, multi-disciplinary and international program started in 2012 (https://www.atm.helsinki.fi/peex/). PEEX sets a research approach by which large-scale research topics are investigated from a system perspective and which aims to fill the key gaps in our understanding of the feedbacks and interactions between the land-atmosphereaquatic-society continuum in the northern Eurasian region. We introduce here the state of the art for the key topics in the PEEX research agenda and present the future prospects of the research, which we see relevant in this context.
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| 2. |
- Filatov, Alexander, et al.
(author)
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Negative differential resistance in magnetic tunnel junction systems
- 2014
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In: Physica Status Solidi B-Basic Solid State Physics. - : Wiley. - 0370-1972 .- 1521-3951. ; 251:1, s. 172-177
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Journal article (peer-reviewed)abstract
- We study the electrophysical properties of the Fe/MgO/Fe magnetic tunnel junctions (MTJ) with impurities. Sample structures are fabricated on top of fine-crystalline glass-ceramic substrates by e-beam evaporation in a relatively low vacuum (approximate to 10(-4)Torr). The influence of the first magnetic layer fabrication conditions on the degradation of the MTJ is explained by the interlayer diffusion. Various models of electrophysical processes in MTJ on polycrystalline substrates are discussed. The current-voltage (I-V) characteristics of the fabricated structures are found to exhibit a region with negative differential resistance, similar to the one in tunneling diodes. We explain this phenomenon by the formation of excitons in the MgO layer modified by the conductive impurity atoms and their diffusion. The obtained results will be useful in the development of MRAM devices containing MTJs and tunneling diodes. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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| 3. |
- Byazrova, Maria, et al.
(author)
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Dissection of Antibody Responses of Gam-COVID-Vac-Vaccinated Subjects Suggests Involvement of Epitopes Outside RBD in SARS-CoV-2 Neutralization
- 2023
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In: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 24:6
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Journal article (peer-reviewed)abstract
- Millions of people have been vaccinated with Gam-COVID-Vac but fine specificities of induced antibodies have not been fully studied. Plasma from 12 naïve and 10 coronavirus disease 2019 (COVID-19) convalescent subjects was obtained before and after two immunizations with Gam-COVID-Vac. Antibody reactivity in the plasma samples (n = 44) was studied on a panel of micro-arrayed recombinant folded and unfolded severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) proteins and 46 peptides spanning the spike protein (S) and by immunoglobulin G (IgG) subclass enzyme-linked immunosorbent assay (ELISA). The ability of Gam-COVID-Vac-induced antibodies to inhibit binding of the receptor-binding domain (RBD) to its receptor angiotensin converting enzyme 2 (ACE2) was investigated in a molecular interaction assay (MIA). The virus-neutralizing capacity of antibodies was studied by the pseudo-typed virus neutralization test (pVNT) for Wuhan-Hu-1 and Omicron. We found that Gam-COVID-Vac vaccination induced significant increases of IgG1 but not of other IgG subclasses against folded S, spike protein subunit 1 (S1), spike protein subunit 2 (S2), and RBD in a comparable manner in naïve and convalescent subjects. Virus neutralization was highly correlated with vaccination-induced antibodies specific for folded RBD and a novel peptide (i.e., peptide 12). Peptide 12 was located close to RBD in the N-terminal part of S1 and may potentially be involved in the transition of the pre- to post-fusion conformation of the spike protein. In summary, Gam-COVID-Vac vaccination induced S-specific IgG1 antibodies in naive and convalescent subjects in a comparable manner. Besides the antibodies specific for RBD, the antibodies induced against a peptide close to the N-terminus of RBD were also associated with virus-neutralization.
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| 4. |
- Gozem, Samer, et al.
(author)
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Shape of Multireference, Equation-of-Motion Coupled-Cluster, and Density Functional Theory Potential Energy Surfaces at a Conical Intersection
- 2014
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In: Journal of Chemical Theory and Computation. - : American Chemical Society (ACS). - 1549-9618 .- 1549-9626. ; 10:8, s. 3074-3084
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Journal article (peer-reviewed)abstract
- We report and characterize ground-state and excited-state potential energy profiles using a variety of electronic structure methods along a loop lying on the branching plane associated with a conical intersection (Cl) of a reduced retinal model, the penta-2,4-dieniminium cation (PSB3). Whereas the performance of the equation-of-motion coupled-duster, density functional theory, and multireference methods had been tested along the excited- and ground-state paths of PSB3 in our earlier work, the ability of these methods to correctly describe the potential energy surface shape along a CI branching plane has not yet been investigated. This is the focus of the present contribution. We find, in agreement with earlier studies by others, that standard time-dependent DFT (TDDFT) does not yield the correct two-dimensional (i.e., conical) crossing along the branching plane but rather a one-dimensional (i.e., linear) crossing along the same plane. The same type of behavior is found for SS-CASPT2(IPEA=0), SS-CASPT2(IPEA=0.25), spin-projected SF-TDDFT, EOM-SF-CCSD, and, finally, for the reference MRCISD+Q method. In contrast, we found that MRCISD, CASSCF, MS-CASPT2(IPEA=0), MS-CASPT2(IPEA=0.25), XMCQDPT2, QD-NEVPT2, non-spin-projected SF-TDDFT, and SI-SA-REKS yield the expected conical crossing. To assess the effect of the different crossing topologies (i.e., linear or conical) on the PSB3 photoisomerization efficiency, we discuss the results of 100 semiclassical trajectories computed by CASSCF and SS-CASPT2(IPEA=0.25) for a PSB3 derivative. We show that for the same initial conditions, the two methods yield similar dynamics leading to isomerization quantum yields that differ by only a few percent.
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| 5. |
- Perepelov, Andrei V., et al.
(author)
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Structure and genetics of the O-antigen of Escherichia coli O169 related to the O-antigen of Shigella boydii type 6
- 2015
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In: Carbohydrate Research. - : Elsevier BV. - 0008-6215 .- 1873-426X. ; 414, s. 46-50
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Journal article (peer-reviewed)abstract
- The O-polysaccharide (O-antigen) of Escherichia coli O169 was studied by sugar analysis along with 1D and 2D H-1 and C-13 NMR spectroscopy. The following structure of the branched hexasaccharide repeating unit was established: [GRAPHICS] The O-polysaccharide of E. coli O169 differs from that of Shigella boydii type 6 only in the presence of a side-chain glucose residue. A comparison of the O-antigen biosynthesis gene clusters between the galF to gnd genes in the genomes of the two bacteria revealed their close relationship. The glycosyltransferase gene responsible for the formation of the beta-D-Glcp-(1 -> 6)-alpha-D-Galp linkage in the O-antigen was identified in the gene cluster.
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| 6. |
- Perepelov, Andrei V., et al.
(author)
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Structures and gene clusters of the closely related O-antigens of Escherichia coli O46 and O134, both containing D-glucuronoyl-D-allothreonine
- 2015
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In: Carbohydrate Research. - : Elsevier BV. - 0008-6215 .- 1873-426X. ; 409, s. 20-24
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Journal article (peer-reviewed)abstract
- The O-polysaccharides (O-antigens) were isolated by mild acid degradation of the lipopolysaccharide (LPS) of Escherichia coli O46 and O134. The structures of their linear tetrasaccharide repeating units were established by sugar analysis along with 1D and 2D H-1 and C-13 NMR spectroscopy: [GRAPHICS] where D-aThr indicates D-allothreonine and R indicates O-acetyl substitution (similar to 70% on aThr and similar to 15% on GalNAc) in E. coli O46 whereas the O-acetylation is absent in E. coli O134. Functions of genes in the essentially identical O-antigen gene clusters of E. coli O46 and O134 were tentatively assigned by a comparison with sequences in available databases and found to be in agreement with the O-polysaccharide structures established.
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| 7. |
- Smirnov, A.N., et al.
(author)
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Measurement of neutron-induced fission cross-sections for natPb, 208Pb, 197Au, natW, and 181Ta in the intermediate energy region
- 2004
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 70:5, s. 054603-
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Journal article (peer-reviewed)abstract
- Neutron-induced fission cross-section ratios natPb∕209Bi, 208Pb∕209Bi, 197Au∕209Bi, natW∕209Bi, 181Ta∕209Bi, and 209Bi∕238U have been measured in the 30–180 MeV energy range using the neutron beam facility at The Svedberg Laboratory in Uppsala. The 7Li(p,n) reaction was employed as a neutron source. The fission fragments were detected by thin-film breakdown counters. Cross sections at specific energies were determined using unfolding techniques with respect to the excitation function and the neutron spectra, the latter obtained from recent measurements and an evaluation. The absolute fission cross sections were obtained using the standard 238U(n,f) cross section. The natW(n,f) and 181Ta(n,f) cross sections have been measured for the first time. The results for 209Bi(n,f), natPb(n,f), 208Pb(n,f), and 197Au(n,f) cross sections have been compared with available literature data. A universal easy-to-use parametrization has been suggested for all measured cross sections. The common features of subactinide neutron-induced fission cross sections are found to be similar to those of the proton-induced fission data.
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| 8. |
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| 9. |
- Yang, Yuanting, et al.
(author)
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The characterization of CD8+ T-cell responses in COVID-19
- 2024
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In: EMERGING MICROBES & INFECTIONS. - 2222-1751. ; 13:1
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Research review (peer-reviewed)abstract
- This review gives an overview of the protective role of CD8(+) T cells in SARS-CoV-2 infection. The cross-reactive responses intermediated by CD8(+) T cells in unexposed cohorts are described. Additionally, the relevance of resident CD8(+) T cells in the upper and lower airway during infection and CD8(+) T-cell responses following vaccination are discussed, including recent worrisome breakthrough infections and variants of concerns (VOCs). Lastly, we explain the correlation between CD8(+) T cells and COVID-19 severity. This review aids in a deeper comprehension of the association between CD8(+) T cells and SARS-CoV-2 and broadens a vision for future exploration.
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