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Čitar M, Hacin B, Tompa G, Štempelj M, Rogelj I, Dolinšek J, Narat M, Matijašić BB. Human intestinal mucosa-associated Lactobacillus and Bifidobacterium strains with probiotic properties modulate IL-10, IL-6 and IL-12 gene expression in THP-1 cells. Benef Microbes 2015; 6:325-36. [DOI: 10.3920/bm2014.0081] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Lactobacilli and bifidobacteria are considered one of the permanent genera of the physiological human intestinal microbiota and represent an enormous pool of potential probiotic candidates. Approximately 450 isolates of presumptive Lactobacillus or Bifidobacterium strains were obtained from bioptic samples of colonic and ileal mucosa from 15 adolescents aged 12 to 18 years. On the basis of randomly amplified polymorphic DNA (RAPD)-PCR analysis, 20 strains were selected for further taxonomic classification and characterisation, as well as assessment of probiotic properties and safety. Importantly, selected strains showed the capability of colonising different parts of the intestine. The most frequently isolated species was Lactobacillus paracasei followed by Lactobacillus fermentum. The majority of isolates were susceptible to antimicrobials of human and veterinary importance, however, tetracycline and/or erythromycin resistance was observed in Lactobacillus plantarum and L. fermentum strains. Thirteen strains were able to ferment more than 19 different carbon sources and three out of five tested strains exerted antagonistic activity against several different indicator strains. Two Lactobacillus isolates (L. paracasei L350 and L. fermentum L930 bb) and one Bifidobacterium isolate (Bifidobacterium animalis subsp. animalis IM386) fulfilled in vitro selection criteria for probiotic strains and exhibited strong downregulation of pro-inflammatory cytokines IL-6 and IL-12 and upregulation of anti-inflammatory IL-10. The selected strains represent suitable candidates for further studies regarding their positive influence on host health and could play an important role in ameliorating the symptoms of inflammatory bowel diseases.
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Affiliation(s)
- M. Čitar
- Biotechnical Faculty, Department of Animal Science, Institute of Dairy Science and Probiotics, University of Ljubljana, Groblje 3, 1230 Domžale, Slovenia
- Medis, Pharmaceutical Company, d.o.o., Brnčičeva 1, 1231 Ljubljana, Slovenia
| | - B. Hacin
- Veterinary Faculty, National Veterinary Institute, Pri Hrastu 18, 5000 Nova Gorica, Slovenia
| | - G. Tompa
- Biotechnical Faculty, Department of Animal Science, Institute of Dairy Science and Probiotics, University of Ljubljana, Groblje 3, 1230 Domžale, Slovenia
| | - M. Štempelj
- Medis, Pharmaceutical Company, d.o.o., Brnčičeva 1, 1231 Ljubljana, Slovenia
| | - I. Rogelj
- Biotechnical Faculty, Department of Animal Science, Institute of Dairy Science and Probiotics, University of Ljubljana, Groblje 3, 1230 Domžale, Slovenia
| | - J. Dolinšek
- Department of Pediatrics, Gastroenterology, hepatology and nutrition Unit, University Medical Centre Maribor, Ljubljanska ulica 5, 2000 Maribor, Slovenia
| | - M. Narat
- Biotechnical Faculty, Department of Animal Science, Chair of Genetics, Animal Biotechnology and Immunology, University of Ljubljana, Groblje 3, 1230 Domžale, Slovenia
| | - B. Bogovič Matijašić
- Biotechnical Faculty, Department of Animal Science, Institute of Dairy Science and Probiotics, University of Ljubljana, Groblje 3, 1230 Domžale, Slovenia
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Koželj P, Vrtnik S, Jelen A, Jazbec S, Jagličić Z, Maiti S, Feuerbacher M, Steurer W, Dolinšek J. Discovery of a superconducting high-entropy alloy. Phys Rev Lett 2014; 113:107001. [PMID: 25238377 DOI: 10.1103/physrevlett.113.107001] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2014] [Indexed: 06/03/2023]
Abstract
High-entropy alloys (HEAs) are multicomponent mixtures of elements in similar concentrations, where the high entropy of mixing can stabilize disordered solid-solution phases with simple structures like a body-centered cubic or a face-centered cubic, in competition with ordered crystalline intermetallic phases. We have synthesized an HEA with the composition Ta34Nb33Hf8Zr14Ti11 (in at. %), which possesses an average body-centered cubic structure of lattice parameter a=3.36 Å. The measurements of the electrical resistivity, the magnetization and magnetic susceptibility, and the specific heat revealed that the Ta34Nb33Hf8Zr14Ti11 HEA is a type II superconductor with a transition temperature Tc≈7.3 K, an upper critical field μ0H_c2≈8.2 T, a lower critical field μ0Hc1≈32 mT, and an energy gap in the electronic density of states (DOS) at the Fermi level of 2Δ≈2.2 meV. The investigated HEA is close to a BCS-type phonon-mediated superconductor in the weak electron-phonon coupling limit, classifying it as a "dirty" superconductor. We show that the lattice degrees of freedom obey Vegard's rule of mixtures, indicating completely random mixing of the elements on the HEA lattice, whereas the electronic degrees of freedom do not obey this rule even approximately so that the electronic properties of a HEA are not a "cocktail" of properties of the constituent elements. The formation of a superconducting gap contributes to the electronic stabilization of the HEA state at low temperatures, where the entropic stabilization is ineffective, but the electronic energy gain due to the superconducting transition is too small for the global stabilization of the disordered state, which remains metastable.
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Affiliation(s)
- P Koželj
- Faculty of Mathematics and Physics, J. Stefan Institute and University of Ljubljana, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - S Vrtnik
- Faculty of Mathematics and Physics, J. Stefan Institute and University of Ljubljana, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - A Jelen
- Faculty of Mathematics and Physics, J. Stefan Institute and University of Ljubljana, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - S Jazbec
- Faculty of Mathematics and Physics, J. Stefan Institute and University of Ljubljana, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - Z Jagličić
- Faculty of Civil and Geodetic Engineering, Institute of Mathematics, Physics and Mechanics and University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia
| | - S Maiti
- Department of Materials, Laboratory of Crystallography, ETH Zürich, Vladimir-Prelog-Weg 5, CH-8093 Zürich, Switzerland
| | - M Feuerbacher
- Institut für Mikrostrukturforschung, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - W Steurer
- Department of Materials, Laboratory of Crystallography, ETH Zürich, Vladimir-Prelog-Weg 5, CH-8093 Zürich, Switzerland
| | - J Dolinšek
- Faculty of Mathematics and Physics, J. Stefan Institute and University of Ljubljana, Jamova 39, SI-1000 Ljubljana, Slovenia
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Abstract
The 14N electric field gradient tensors have been determined in the paraelectric phase at T = 26 °C and in the incommensurate phase at T = 16 °C. The results in the incommensurate phase are typical for the “non-local” case and show the presence of two out of phase components of the modulation wave. The phase shift between the linear and the quadratic terms in the expansion of the frequency in powers of the order parameter is as large as 45°.
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Affiliation(s)
- J. Dolinšek
- J. Stefan Institute, E. Kardelj University of Ljubljana, Ljubljana, Yugoslavia
| | - R. Blinc
- J. Stefan Institute, E. Kardelj University of Ljubljana, Ljubljana, Yugoslavia
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Vrtnik S, Jazbec S, Jagodič M, Korelec A, Hosnar L, Jagličić Z, Jeglič P, Feuerbacher M, Mizutani U, Dolinšek J. Stabilization mechanism of γ-Mg₁₇Al₁₂ and β-Mg₂Al₃ complex metallic alloys. J Phys Condens Matter 2013; 25:425703. [PMID: 24080784 DOI: 10.1088/0953-8984/25/42/425703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Large-unit-cell complex metallic alloys (CMAs) frequently achieve stability by lowering the kinetic energy of the electron system through formation of a pseudogap in the electronic density of states (DOS) across the Fermi energy εF. By employing experimental techniques that are sensitive to the electronic DOS in the vicinity of εF, we have studied the stabilization mechanism of two binary CMA phases from the Al-Mg system: the γ-Mg17Al12 phase with 58 atoms in the unit cell and the β-Mg2Al3 phase with 1178 atoms in the unit cell. Since the investigated alloys are free from transition metal elements, orbital hybridization effects must be small and we were able to test whether the alloys obey the Hume-Rothery stabilization mechanism, where a pseudogap in the DOS is produced by the Fermi surface-Brillouin zone interactions. The results have shown that the DOS of the γ-Mg17Al12 phase exhibits a pronounced pseudogap centered almost exactly at εF, which is compatible with the theoretical prediction that this phase is stabilized by the Hume-Rothery mechanism. The disordered cubic β-Mg2Al3 phase is most likely entropically stabilized at high temperatures, whereas at lower temperatures stability is achieved by undergoing a structural phase transition to more ordered rhombohedral β' phase at 214 ° C, where all atomic sites become fully occupied. No pseudogap in the vicinity of εF was detected for the β' phase on the energy scale of a few 100 meV as determined by the 'thermal observation window' of the Fermi-Dirac function, so that the Hume-Rothery stabilization mechanism is not confirmed for this compound. However, the existence of a much broader shallow pseudogap due to several critical reciprocal lattice vectors [Formula: see text] that simultaneously satisfy the Hume-Rothery interference condition remains the most plausible stabilization mechanism of this phase. At Tc = 0.85 K, the β' phase undergoes a superconducting transition, which slightly increases the cohesive energy and may contribute to relative stability of this phase against competing neighboring phases.
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Affiliation(s)
- S Vrtnik
- J Stefan Institute and University of Ljubljana, Faculty of Mathematics and Physics, Jamova 39, SI-1000 Ljubljana, Slovenia
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Klanjšek M, Gradišek A, Kocjan A, Bobnar M, Jeglič P, Wencka M, Jagličić Z, Popčević P, Ivkov J, Smontara A, Gille P, Armbrüster M, Grin Y, Dolinšek J. PdGa intermetallic hydrogenation catalyst: an NMR and physical property study. J Phys Condens Matter 2012; 24:085703. [PMID: 22310701 DOI: 10.1088/0953-8984/24/8/085703] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The PdGa intermetallic compound is a highly selective and stable heterogeneous hydrogenation catalyst for the semi-hydrogenation of acetylene. We have studied single crystals of PdGa grown by the Czochralski technique. The (69)Ga electric-field-gradient (EFG) tensor was determined by means of NMR spectroscopy, giving experimental confirmation of both the recently refined structural model of PdGa and the theoretically predicted Pd-Ga covalent bonding scheme. The hydrogenation experiment has detected no hydrogen uptake in the PdGa, thus preventing in situ hydride formation that leads to a reduction of the catalytic selectivity. We have also determined bulk physical properties (the magnetic susceptibility, the electrical resistivity, the thermoelectric power, the Hall coefficient, the thermal conductivity and the specific heat) of single-crystalline PdGa. The results show that PdGa is a diamagnet with metallic electrical resistivity and moderately high thermal conductivity. The thermoelectric power is negative with complicated temperature dependence, whereas the Hall coefficient is positive and temperature-dependent, indicating complexity of the Fermi surface. Partial fulfillment of the NMR Korringa relation reveals that the charge carriers are weakly correlated. Specific heat measurements show that the density of electronic states (DOS) at the Fermi energy of PdGa is reduced to 15% of the DOS of the elemental Pd metal.
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Affiliation(s)
- M Klanjšek
- J. Stefan Institute and University of Ljubljana, Faculty of Mathematics and Physics, Ljubljana, Slovenia
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Sobočan U, Lee G, Kang HW, Kim HJ, Jagličić Z, Dolinšek J. The Nature of Magnetic State of Small Fe3O4 Nanoparticles. J Anal Sci Technol 2011. [DOI: 10.5355/jast.2011.a8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Gradišek A, Dimnik B, Vrtnik S, Wencka M, Zdanowska Fraczek M, Lavrova GV, Dolinšek J. The hydrogen dynamics of CsH5(PO4)2 studied by means of nuclear magnetic resonance. J Phys Condens Matter 2011; 23:085901. [PMID: 21411903 DOI: 10.1088/0953-8984/23/8/085901] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We have investigated the hydrogen dynamics of cesium pentahydrogen diphosphate, CsH(5)(PO(4))(2), by means of nuclear magnetic resonance (NMR) spectroscopy, in order to address the question of why there is no superprotonic phase transition in this compound, in contrast to other structurally similar hydrogen-bonded ionic salts, where a superprotonic transition is frequently found to be present. The analysis of the NMR spectrum and the spin-lattice relaxation rate revealed that the temperature-dependent hydrogen dynamics of CsH(5)(PO(4))(2) involves motional processes (the intra-H-bond jumps and the inter-H-bond jumps at elevated temperatures, as a mechanism of the ionic conductivity) identical to those for the other H-bonded superprotonic salts. The considerably stronger H-bond network in CsH(5)(PO(4))(2) prompts the search for a higher superprotonic transition temperature. However, due to the relatively weak bonding between the {[H(2)PO(4)]}∞ planes in the [100] direction of the CsH(5)(PO(4))(2) structure by means of the ionic bonding via the cesium atoms and the small number of H bonds in that direction (where out of five H bonds in the unit cell, four are directed within the {[H(2)PO(4)]}∞ planes and only one is between the planes), the bonds between the planes become thermally broken and the crystal melts before the H-bond network rearranges via water release into an open structure typical of the superprotonic phase. Were the coupling between the {[H(2)PO(4)]}∞ planes in the CsH(5)(PO(4))(2) somewhat stronger, the superprotonic transition would occur in the same manner as it does in other structurally related hydrogen-bonded ionic salts.
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Affiliation(s)
- A Gradišek
- J Stefan Institute, University of Ljubljana, Jamova 39, SI-1000 Ljubljana, Slovenia
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Jazbec S, Jagličić Z, Vrtnik S, Wencka M, Feuerbacher M, Heggen M, Roitsch S, Dolinšek J. Geometric origin of magnetic frustration in the μ-Al₄Mn giant-unit-cell complex intermetallic. J Phys Condens Matter 2011; 23:045702. [PMID: 21406894 DOI: 10.1088/0953-8984/23/4/045702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The structurally ordered μ-Al(4)Mn complex intermetallic phase with 563 atoms in the giant unit cell shows the typical broken-ergodicity phenomena of a magnetically frustrated spin system. The low-field zero-field-cooled and field-cooled magnetic susceptibilities show splitting below the spin freezing temperature T(f) = 2.7 K. The ac susceptibility exhibits a frequency-dependent cusp, associated with a frequency-dependent freezing temperature T(f)(ν). The decay of the thermoremnant magnetization is logarithmically slow in time and shows a dependence on the aging time t(w) and the cooling field H(fc) typical of an ultraslow out-of-equilibrium dynamics of a nonergodic spin system that approaches thermal equilibrium, but can never reach it on the experimentally accessible time scale. The above features classify the μ-Al(4)Mn complex intermettalic among spin glasses. The origin of frustration of magnetic interactions was found to be geometrical due to the distribution of a significant fraction of Mn spins on triangles with antiferromagnetic coupling. The μ-Al(4)Mn phase is a geometrically frustrated spin glass.
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Affiliation(s)
- S Jazbec
- J Stefan Institute, University of Ljubljana, Jamova 39, SI-1000 Ljubljana, Slovenia
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Jagodič M, Jagličić Z, Jelen A, Lee JB, Kim YM, Kim HJ, Dolinšek J. Surface-spin magnetism of antiferromagnetic NiO in nanoparticle and bulk morphology. J Phys Condens Matter 2009; 21:215302. [PMID: 21825545 DOI: 10.1088/0953-8984/21/21/215302] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The surface-spin magnetism of the antiferromagnetic (AFM) material NiO in nanoparticle and bulk morphology was investigated by magnetic measurements (temperature-dependent zero-field-cooled (zfc) and field-cooled (fc) dc susceptibility, ac susceptibility and zfc and fc hysteresis loops). We addressed the question of whether the multisublattice ordering of the uncompensated surface spins and the exchange bias (EB) effect are only present in the nanoparticles, originating from their high surface-to-volume ratio or if these surface phenomena are generally present in the AFM materials regardless of their bulky or nanoparticle morphology, but the effect is just too small to be detected experimentally in the bulk due to a very small surface magnetization. Performing experiments on the NiO nanoparticles of different sizes and bulk NiO grains, we show that coercivity enhancement and hysteresis loop shift in the fc experiments, considered to be the key experimental manifestations of multisublattice ordering and the EB effect, are true nanoscale phenomena only present in the nanoparticles and absent in the bulk.
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Affiliation(s)
- M Jagodič
- Institute of Mathematics, Physics and Mechanics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia
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Kim H, Lee J, Kim YM, Jung MH, Jagličić Z, Umek P, Dolinšek J. Synthesis, structure and magnetic properties of β-MnO 2nanorods. Nanoscale Res Lett 2007; 2:81. [PMCID: PMC3245568 DOI: 10.1007/s11671-006-9034-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2006] [Accepted: 12/08/2006] [Indexed: 05/29/2023]
Abstract
We present synthesis, structure and magnetic properties of structurally well-ordered single-crystalline β-MnO2nanorods of 50–100 nm diameter and several µm length. Thorough structural characterization shows that the basic β-MnO2material is covered by a thin surface layer (∼2.5 nm) of α-Mn2O3phase with a reduced Mn valence that adds its own magnetic signal to the total magnetization of the β-MnO2nanorods. The relatively complicated temperature-dependent magnetism of the nanorods can be explained in terms of a superposition of bulk magnetic properties of spatially segregated β-MnO2and α-Mn2O3constituent phases and the soft ferromagnetism of the thin interface layer between these two phases.
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Affiliation(s)
- HaeJin Kim
- Energy Nano Material Team, Korea Basic Science Institute, Daejeon, 305-806, Korea
| | - JinBae Lee
- Energy Nano Material Team, Korea Basic Science Institute, Daejeon, 305-806, Korea
| | - Young-Min Kim
- Division of Electron Microscopic Research, Korea Basic Science Institute, Daejeon, 305-806, Korea
| | - Myung-Hwa Jung
- Quantum Material Research Team, Korea Basic Science Institute, Daejeon, 305-806, Korea
| | - Z Jagličić
- Institute of Mathematics, Physics and Mechanics, Jadranska 19, Ljubljana, 1000, Slovenia
| | - P Umek
- J. Stefan Institute, University of Ljubljana, Jamova 39, Ljubljana, 1000, Slovenia
| | - J Dolinšek
- J. Stefan Institute, University of Ljubljana, Jamova 39, Ljubljana, 1000, Slovenia
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Vrbančič N, Vilfan M, Blinc R, Dolinšek J, Crawford GP, Doane JW. Deuteron spin relaxation and molecular dynamics of a nematic liquid crystal (5CB) in cylindrical microcavities. J Chem Phys 1993. [DOI: 10.1063/1.464074] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Dolinšek J, Jarh O, Vilfan M, Žumer S, Blinc R, Doane JW, Crawford G. Two‐dimensional deuteron nuclear magnetic resonance of a polymer dispersed nematic liquid crystal. J Chem Phys 1991. [DOI: 10.1063/1.461014] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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14
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Vilfan M, Blinc R, Dolinšek J, Ipavec M, Lahajnar G, Žumer S. Dispersion of proton spin-lattice relaxation in a cholesteric liquid crystal. ACTA ACUST UNITED AC 1983. [DOI: 10.1051/jphys:0198300440100117900] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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